Audacity doesn’t recognise .au-files

I use Linux Manjaro, Audacity-version is 2.4.1 , installed from the repository.

Whenever I try to open an Audacity project, I get an empty track and the message (translation from German, don’t know the English version):
“Examination of Folder “…_data” found …nn… orphaned [??] ?-files [“Blockdateien”] etc.”
…nn… is exactly the number of .au-files in the project folder. It’s the same problem both with old and newly created projects.
Thanks for your help!