PDF document corrupt after editing in DTTG 3.0.5


I have been working on a PDF document (13 pages) in Devonthink To Go for a few days. Basically, I created annotations in the form of underlining, highlighting and margin notes using the Apple Pencil. Everything worked smoothly. Today, while editing, the document showed up as corrupt: 5.4 MBytes, 0 pages. Both the text and the annotations have disappeared. Attempting to open the file with another PDF editor failed. Acrobat Pro DC reports “Error 14” and crashes when trying to view the “Advanced Properties” of the document. After detecting the error, I could see that the document was still correct in DT3. After some time (after synchronization?) the document could not be opened in Devonthink 3 either. Instead, only a preview image is displayed.
A few days ago I had a similar phenomenon: there, while editing a PDF document (about 15 pages), the text on one page disappeared and only the highlights were displayed on that page.
Because of the backup, none of the cases lost a lot of work. But this should not happen.

iOS 14.4.2 on iPad Pro
Devonthink To Go (3.0.5 (17053))
macOS 11.2.3
Devonthink 3.6.3
PDF version of the document 1.3, Acrobat 4

Kind regards

Translated with www.DeepL.com/Translator (free version)

In DEVONthink To Go, select Help > Contact Us to start a Support Ticket. Thanks!

Thank you very much for the quick response.
I have opened the ticket.