Scripting Issue that only occurs on Windows

Try running the script straight from the Scripts Menu, skip the Script Panel to see if it works.

Hi @ict-opr I suspect the copy/pasting is adding something strange to the text string, maybe an invisible character, and I would try filtering the string to remove anything that isn't an expected character—let me know if you want to do that.

But, just for learning, I've written a version of your scripts combined into a single palette. It should—hopefully!— remove the error you are seeing because it doesn't do the string copy/pasting that your current workflow uses. I hope it will be useful, at least as a starting point. I apologize for the mess of BridgeTalk nonsense in the script but that is just what we have to do to use a palette, as opposed to a dialog.

Let me know how it goes.

- Mark

/**
 * @file Position Items.js
 *
 * Variation of user @ict-opr's two scripts
 * showing use of palette to load positions
 * and later use them to position items.
 *
 * @author m1b
 * @version 2025-09-26
 * @discussion https://community.adobe.com/t5/illustrator-discussions/scripting-issue-that-only-occurs-on-windows/m-p/15520320
 */
//@targetengine 'positionItems'
(function () {

    // check if the window already exists by using a global variable
    if (
        "undefined" !== typeof $.global.palette
        && null !== $.global.palette
    ) {
        // NOTE: while debugging, you will want to disable this part
        // because it will stop your new palette from instantiating
        // (otherwise you'll need to restart Illustrator each time!)
        $.global.palette.active = true;
        $.global.palette.show();
        return;
    }

    // create a new ScriptUI palette (modeless window)
    $.global.palette = new Window("palette", "Position Items", undefined, { resizeable: false });

    const FIELD_DELIMITER = ';';
    const ITEM_DELIMITER = '$';

    var activePositions = '';

    var buttons = palette.add('group {orientation: "row", alignment:["fill","top"], alignChildren:["fill","top"] }');
    // var loadGroup = buttons.add('group {orientation: "column", alignChildren:["left","top"] }');
    var loadButton = buttons.add('button { text:"Load" }');
    // var positionGroup = buttons.add('group {orientation: "row", alignChildren:["left","top"] }');
    var positionButton = buttons.add('button { text:"Position" }');
    var loadedLabel = palette.add('statictext {text:"", alignment:["fill","top"], justify:"center" }');
    var resizeCheckbox = buttons.add('checkbox {text:"Resize Items", alignment:["fill","bottom"] }');

    /** load button is clicked - send `loadPositions` function to Illustrator */
    loadButton.onClick = function () {

        // a BridgeTalk message
        var bt = new BridgeTalk();
        bt.target = "illustrator";

        // convert the function to a string IIFE
        // this is a way to send code via bridgeTalk
        bt.body = "(" + loadPositions.toSource() + ")(#I,#F);"
            // include string parameters
            .replace('#I', '"' + ITEM_DELIMITER + '"')
            .replace('#F', '"' + FIELD_DELIMITER + '"');

        // handle the result returned from Illustrator
        bt.onResult = function (response) {
            activePositions = response.body || '';
            updateUI();
        };

        // send the script to Illustrator
        bt.send();

    };

    /** position button is clicked - send `positionItems` function to Illustrator */
    positionButton.onClick = function () {

        // a BridgeTalk message
        var bt = new BridgeTalk();
        bt.target = "illustrator";

        // convert the function to a string IIFE
        // this is a way to send code via bridgeTalk
        bt.body = "(" + positionItems.toSource() + ")(#P,#R,#I,#F);"
            // include string parameters
            .replace('#P', '"' + activePositions + '"')
            .replace('#R', '"' + (resizeCheckbox.value ? '1' : '') + '"')
            .replace('#I', '"' + ITEM_DELIMITER + '"')
            .replace('#F', '"' + FIELD_DELIMITER + '"');

        // send the script to Illustrator
        bt.send();

    };

    // show the palette
    updateUI();
    palette.center();
    palette.show();

    /** update the UI - positions count and button enabling */
    function updateUI() {
        var positionCount = (activePositions.split(ITEM_DELIMITER).length - 1);
        loadedLabel.text = positionCount + ' positions ready.';
        positionButton.enabled = positionCount > 0;
        resizeCheckbox.enabled = positionCount > 0;
    };

    /**
     * Returns a `positions` string from selected objects.
     * To be sent to Illustrator via BridgeTalk
     * @param {String} itemDelimiter - string to add between item position strings.
     * @param {String} fieldDelimiter - string to add between fields of an item position string.
     * @returns {String} - the position(s).
     */
    function loadPositions(itemDelimiter, fieldDelimiter) {

        /*
            IMPORTANT: you must use block comments in any function
            that you will be sending via BridgeTalk, because it seems
            to evaluate the whole body as a single line, therefore
            an inline comment will nullify everything after it.
        */
        if (0 === app.documents.length)
            return alert("Please open a document and try again.");

        var doc = app.activeDocument;
        var items = doc.selection;

        if (0 === items.length)
            return alert("Please select some page items and try again.");

        var positions = '';

        /* build the positions string */
        for (var i = 0, item; i < items.length; i++) {
            item = items[i];
            positions += [item.left, item.top, item.width, item.height].join(fieldDelimiter) + itemDelimiter;
        }

        return positions;

    };

    /**
     * Positions selected items according
     * to `activePositions` string.
     * To be sent to Illustrator via BridgeTalk
     * @param {String} positions - the positions to use.
     * @param {String} [resize] - whether to resize the item (default: do not resize).
     * @param {String} itemDelimiter - string to add between item position strings.
     * @param {String} fieldDelimiter - string to add between fields of an item position string.
     */
    function positionItems(positions, resize, itemDelimiter, fieldDelimiter) {

        /*
            IMPORTANT: you must use block comments in any function
            that you will be sending via BridgeTalk, because it seems
            to evaluate the whole body as a single line, therefore
            an inline comment will nullify everything after it.
        */

        var scaleMultiplier = 1;

        if (0 === app.documents.length)
            return alert("Please open a document and try again.");

        var doc = app.activeDocument;
        var items = doc.selection;
        if (0 === items.length)
            return alert("Please select some page items and try again.");

        positions = positions.split(itemDelimiter);
        var len = Math.min(positions.length, items.length);

        /* position the items */
        for (var i = 0, item, position; i <= len; i++) {

            item = items[i];
            position = positions[i].split(fieldDelimiter);

            var leftPos = Number(position[0]);
            var topPos = Number(position[1]);
            var objWidth = Number(position[2]);
            var objHeight = Number(position[3]);

            item.left = leftPos * scaleMultiplier;
            item.top = topPos * scaleMultiplier;

            if (resize) {
                item.width = (objWidth * scaleMultiplier);
                item.height = (objHeight * scaleMultiplier);
            }

        }

    };

})();

Could you show us the error you get? And even better, post a sample document? (Save as pdf, Illustrator editable). I might not be able to help because I use MacOS but it will be easier for someone else to test on Windows.

- Mark

PS: a tip—just call your `convUnit` mm, its much easier to understand:

const mm = 2.834645;

var doc = app.activeDocument;
var tf = doc.textFrames.add();
tf.contents = doc.name;
tf.top = 10 * mm;
tf.left = 5 * mm;

 or look at the built-in UnitValue object which handles unit conversions in a more formal way, but I don't usually bother with, personally.

Also the convUnit thing you see everywhere is to convert back and forth between Illustrator's internal unit system and millimeters since I can't directly tell the script to interpret values as mm