SUMMARY

KDE applications like systemsettings or kmail do not show any window when being started.  They keep running in the background with 100% CPU utilisation.  When running them under strace (`strace systemsettings`), the output are lines like the following, over and over again (i.e. I see the same files and folders being scanned again and again, ad infinitum):

openat(AT_FDCWD, "/usr/share/fonts/noto/NotoSans-Regular.ttf", O_RDONLY) = 22
fcntl(22, F_SETFD, FD_CLOEXEC)          = 0
fstat(22, {st_mode=S_IFREG|0644, st_size=509848, ...}) = 0
mmap(NULL, 509848, PROT_READ, MAP_PRIVATE, 22, 0) = 0x7ff7541fd000
close(22)

I am running Sway (Wayland) for my window manager.

STEPS TO REPRODUCE
1. Start Sway
2. Open a terminal
3. Run `strace systemsettings`

OBSERVED RESULT

The same font directories are scanned again and again and no window is shown.


EXPECTED RESULT

I see the system settings window.


SOFTWARE/OS VERSIONS

Linux: 5.8.14
KDE Plasma Version: 5.20.3
KDE Frameworks Version: 5.75.0
Qt Version: 5.15.1

ADDITIONAL INFORMATION

`systemsettings5 --version` says it is version 5.20.2, but my package manager says version 5.20.3 is installed.