I have used KDEnlive under Debian Linux 64 for a year now. Suddenly something changed so that moving the marker of the timeline doesn't move where you are in the clip anymore. Pressing SPACE doesn't start/stop playing anymore either. I deinstalled and reinstalled KDEnlive using Synaptic several times but still same problem. What to do?

KDEnlive 16.08.3
Using:
KDE Frameworks 5.28.0
Qt 5.7.1 (built against 5.7.1)
The xcb windowing system

Could you try to update to 16.12.1 version and test?

Upgraded, but same thing persists. Plus now it said "Cannot initialise Movits GSLS Manager, please disable Movit"

However, running from an AppImage 16.12.0 works normally.