Created attachment 114631 [details] video proof It shows no look and feel themes after switching back to first tab.
I haven't observed that in System Settings but I can when running the two in kcmshell: $ kcmshell5 lookandfeel desktoptheme switch between the two and then the look and feel themes list becomes empty
It seems related to Bug 395442, I can reproduce with kcmshell5 also with other QML KCMs. Suddenly the "kcm" element cannot be accessed anymore, and as such kcm.lookAndFeelModel is undefined and the list turns empty, and also methods like "kcm.installThemeFromFile()" fail.
bug 394632 is related/duplicate.
Yep. Fixed now. *** This bug has been marked as a duplicate of bug 394632 ***