Can't create library in mounted network drive

I mounted my Comics folder from my Samba NAS to ~/Comics but I can't create a YACReader library there.
An error pops up, saying:

Path not found
The selected path does not exist or is not a valid

The rest of the text isn't visible but I can select it and copy it:

The selected path does not exist or is not a valid path. Be sure that you have write access to this folder

I can locate the dir in the file browser, but I can't continue when I press "Create".
It doesn't work with the CIFS mount path like /run/user/1000/doc/534f6538/Comics and it doesn't work if I mount it to /home/myname/Comics either.

Creating a YACReader Library from any local directory works fine, though. Is it a permissions issue?

I installed keyutils and cifs-utils and mounted it again, now I can create the Library, but I get an error trying to open it...

Hmmm. Can you try to create a small local library? An folder with a couple of comics is enough. Does it work?

Yep, just creating a local folder and initializing it as a library works fine for me. It seems to be just folders on the Samba share.

The database used by YACReaderLibrary is sqlite3, you need to mount your volume with the -nobrl option. The symptoms are normally different but it could be that.