@jonas
OK, I searched the bug list but didn't find anything like that. Thank you very much!

Apologies if this is a problem with my equipment. But in versions 1.0.19 and 1.0.20 the MassStorageClass device mount no longer works correctly. Also the iPod mount does not work correctly. The double-click in the device menu does not mount the corresponding drive. The collection, playlist and everything else works fine.

The computer I use is Linux Manjaro with KDE. But I have tried Xfce and it doesn't work either. Finally I have compiled the "old" version 1.0.18 and everything works correctly again. Any suggestions? Thank you very much...!!!!