When I try to install the attached plugin package (.7z file) as "User plugins" nothing happens after I restart Qt Creator. No error dialog or debug text appear, like if the plugin was never installed.

Files are successfully copied to the default installation directory, which in my case is .local/share/data/QtProject/qtcreator/plugins/15.0.0/ 

Things work fine if I try to install the same package as "Qt Creator installation" and the same files are copied to Qt/Tools/QtCreator/lib/qtcreator/plugins/

I never experienced the same problem with other versions of Qt Creator before.