Can't access shares with writing rights with LibreOffice 7.4.7.2

I use LibreOffice on a Raspberry pi 4 with an up-to-date OS (Raspbian-32) and up-to-date packages (I don’t think I can update LibreOffice to a newer version on this device).
I can access network shares and copy files to them or save files to them with other programs.
Yet, I cannot access the shares with write permissions in LibreOffice. Opening as read-only does work.
I can’t save to a network share (“The object cannot be accessed due to insufficient user rights”) or open from a network share with write permissions (“Document is locked for editing by ‘Unknown User’ …”).
Again, I have access to the share with write permissions from other programs.
I’m looking for ideas to troubleshoot the issue.

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