Almost 5 months later - i'm terribly sorry but the end&beginning of the year is totally crazy in this business (more even with all this covid thing)...
That is very odd, that USB SanDisk drive had been ejected and physically removed about an hour prior. The other card reader devices are empty. There...
It's strange. It is somehow related to (my) KDE Plasma environment. If I log in into IceWM, everything works. In plasma I have disabled all autostart...