Upgrade from Office 2021 to 2024 - App Hangs on Save Files

[ragluf]

I have recently upgraded from Office 2021 to Office 2024. However, in Office 2024, all files I have created with Office 2021 are not saving - the application (either Planmaker, TextMaker or Presentations 2024) does hang when any save is done. Just the blue spinning circle. I have again reinstalled Office 2021 and all my files and saves are working again. No issues with these applications.

When in I open a new document or file in Office 2024, and save the new document or file in Office 2024, the file is successfully opened and saved.

This would mean I would have to re-create all my files done in Office 2021 to versions created in Office 2024, which is impossible right now (due to the number).
This is the first time this has happened on any version I have used prior to 2024.

I have retested this scenario - and always happens on any application in Office 2024. I can open all files in Office 2024, but cannot save any changes. With Office 2021, no issues. I have reverted back to Office 2021.

Office 2024 version rev S1234.0411 64bit. Environment is Windows 11 Pro 25H2 26200.8457

Anybody experienced this on the upgrade from 2021 to 2024?