I attached a kernel trace which may be related. I got this when:
1. Upgraded Fedora 24 to Fedora 25.
2. Disabled wayland for gdm.
3. Created script with export QSG_RENDER_LOOP=basic in profile.d.
4. Logged in as a first user to the kde session.
5. Pressed Ctrl+Alt+F1 to get gdm login screen.
6. Logged in as a second user to the kde session.
7. Both kde sessions were stuck, but as opposed to previous behaviour I was able to Ctrl+Alt+Backspace both sessions (maybe because of previous steps I did not use before).
8. After turning down second session got previously attached kernel trace.
I attached a kernel trace which may be related. I got this when:
1. Upgraded Fedora 24 to Fedora 25.
2. Disabled wayland for gdm.
3. Created script with export QSG_RENDER_ LOOP=basic in profile.d.
4. Logged in as a first user to the kde session.
5. Pressed Ctrl+Alt+F1 to get gdm login screen.
6. Logged in as a second user to the kde session.
7. Both kde sessions were stuck, but as opposed to previous behaviour I was able to Ctrl+Alt+Backspace both sessions (maybe because of previous steps I did not use before).
8. After turning down second session got previously attached kernel trace.