Only office does not save files

Hi,
I am testing nextcloud on a local instance with standard http. I installed only office and it creates a word document but it wont save the content back to nextcloud. When I reopen the document the changes are still there so it must remember the content somewhere but the time and date of the file never changes and when I sync the file to my PC it is never updated. When I use “save as” and store the file under a different name it works just fine but when I open and change the new file it is not saved again. When I look at my logs I see two error messages when I open a file with only office but I cant figure out what is my issue here.

The first error is from index and the second from only office.
index error.odt (6,3 KB)
error onlyoffice.odt (13,6 KB)

Anybody knows what is the issue here?

Thx

Stephan