Hi @Der Nordfriese
Acrobat and Reader optional update 22.003.20322 are now available. This update will be automatically pushed to all existing installations of Acrobat and Reader. You may manually trigger the update early by opening the application and going to Help > Check for Updates>reboot Acrobat.
More information about this release is here: Release Notes | Adobe Acrobat, Reader
Check back after installing the update.
If you are saving the document to online storage, follow these steps, disable access to the online storage, and try saving the file locally to see if that works.
Acrobat>Preferences>General>uncheck "Show online storage when saving files">OK
Let us know if that helps.