Howdy,
I think the problem is well known.
Tumbleweed with KDE it is.
When I try to login a freeze occurs. I can move my mouse cursor but nothing else.
It just freezes. Solution ist a hard reset via power button.
Is a patch or something like that available?
The problem exists for a long time with many any versions of opensuse… I think it started with version 12.
In view of some of your other problems… A fresh install might not go amiss, to ensure that all that is intended to be installed, is installed.
Alternatively:
Are you using “X” or “Wayland”? - Wayland is still very much a “work in progress” and, AFAIK is not that reliable when partnered with KDE. (Although others may disagree on that point).
Have you checked the journal for any relevant entries relating to the failed login?
Test with a new user - same problem?
Try using a different DM, lightdm for example - same problem?
As an aside: I’m a long time user of openSUSE and KDE, on the whole it’s proved to be remarkably stable.