After changing secondary display (now HP Z27i, WQHD) and switching to Wayland, it always happens that the largest monitor (32" Iiyama, UHD), which is supposed to be set as primary, loses its status. There is no more way to to define a primary display in KDE system settings. The only way to restore the configuration is to logout and logon again, which is a hassle.
If I choose to turn off the smallest monitor, the session is locked, forcing me to run
$ loginctl unlock-session 2
Has anybody solved this issue so far? Thanks for your support.