Changing the screen rotation under Wayland does not rotate the screen, and hangs the session hard. The mouse does still move, and seems to be constrained to the rotated screen orientation, but the screen does not rotate.
https://paste.kde.org/pqs7un5kq/r0pfrj
The paste from comment #1 is protected. If the information stored there is needed to better understand this issue, I suggest to add this information directly as an attachment.
Created attachment 110388 [details] kwin info
Thanks for the update; I guess it is a duplicate of bug 389665.
The support info is from X11, we need the wayland one.
Created attachment 110706 [details] wayland support.txt
You don't have atomic mode settings enabled. Screen rotation is only supported with atomic mode settings.