Problem with field form tags

Try exporting a "static" version of the file from InDesign, without any form fields.
Then open the old file in Acrobat and use the Replace Pages command to replace the underlying pages with those from the new file. This will keep all of your fields intact, and hopefully their tags, too. Then you just need to adjust them so that they match the new layout, but won't need to re-do all the tagging.

Hi @riccardo_apotema

Thank you for reaching out, and sorry for the troubled experience. There are a number of variables at play for this issue. Please wait for more inputs from experts on this topic. Following are my generic suggestions you can take into account: 

Suggested Steps to Fix or Work Around the Issue:

1. Use “Prepare Form” First, Then Tag the PDF:

• Create and finalize all your form fields using Tools > Prepare Form.

• After all fields are in place, use View > Show/Hide > Navigation Panes > Tags to access the Tags tree.

• Manually adjust the tag names and structure as needed — Acrobat won’t auto-retag at this stage unless triggered.

2. Avoid Auto-Tagging After Manual Edits:

• If you’ve already manually edited tags, avoid running “Autotag Document” again. This will overwrite your custom changes.

• Instead, edit tags directly in the Tags panel, using right-click > Properties to rename or adjust roles.

3. Use Accessibility Checker Carefully:

• When using the Accessibility Checker, Acrobat may try to “fix” issues automatically, sometimes re-tagging form fields.

• Choose Manual Fix wherever possible when dealing with form fields.

4. Check for Duplicate Annotations:

• If tag names are duplicated, it could be because multiple form fields share the same object reference (common after copying fields). Check for duplicates in the Tags and Forms panels.