Resetting Edits after closing and reopening LR Classic

There is no reason to export an edited image and then reset the edits to make new edits. Create a virtual copy if you want to create another edit.

The original raw is always available, because Lightroom doesn't touch it. The edits are written as text to the catalog, and these edits are applied to a new file when you export.

The edits are also applied to the previews you see in Lightroom.

If you want to have an unedited version of an image, create a virtual copy. Select the image, and press Ctrl + ' (apostrophe), or  choose Create virtual copy in the Photo menu.

Or, if you want to start over, click the bottom entry in the History panel (usually "Import"), or click the Reset button.

In Lightroom every step developing a picture is non destructive. It means you can go back every time to the original RAW file. There's a setting in the export options that a exported picture was added to the catalog, so you'll have both.

I've never heard about such a issue.

In a first step I would try to reset the Lightroom preferences. 

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/