Acrobat DC (2021) requires to sign in repeatedly

Hello there!

Some of our users reported lately, that in order to use Acrobat DC they have to sign in with their respectively Adobe ID on a regular basis. An example:

User A is booting his machine (Windows 10 1909 64-bit) in the morning and tries to open a PDF file. Although the cloud app is running, he is asked to enter his Adobe ID. When he does that, it then requires a security code, that is sent to his mailbox. Only after entering said code can he succesfully login to the Adobe Cloud and open the PDF file. This procedure is repeated nearly every single day.

Here are some of the things we already tried:

- Deleting/recreating the local userprofile

- Reinstalling Adobe Acrobat DC completely (incl. Cloud App)

- Updating Acrobat to the latest version

- Anything listed here: https://community.adobe.com/t5/acrobat-discussions/acrobat-keeps-asking-to-sign-in/m-p/11525698

- and here: https://helpx.adobe.com/download-install/kb/acrobat-repeatedly-prompts-for-sign-in.html

- I even tried this procedure here: https://www.youtube.com/watch?v=SGYSZgJqOUo

Said behaviour isn't occuring with all the users, which makes this even more mysterious. No matter what we try, the affected users have to enter their Adobe ID at least once a day, which is driving them nuts in the long run.

In case someone will recommend to update Windows to the latest version (21H1), that isn't possible due to various reasons. But I think it should work with 1909 none the less.

Thx for the help, it is REALLY appreciated.