Tempo completely f...ed in Cubase 10

Lately the tempo in all my projects is completely off. What I mean by that is: The Audio is played correctly as it was recorded, but neither the metronome nor the MIDI content is in the correct tempo or responds to changes in tempo. MIDI is played in the same (slow) tempo, no matter if I activate/deactivate the tempo track or change the tempo. Also the cursor position does not reflect the position of the audio that is played. Meaning that visually it moves across the timeline in sync with the bar counter, so that it looks correct, but what you hear is in a different position. So, in short: visual feedback and audio are out of sync. This doesn´t seem to have anything to do with “musical” or “linear” time basis on the audio tracks - changing that doesn`t fix the problem.

Another issue is that Cubase doesn´t seem to “remember” my audio interface anymore - I have to manually set the audio system as well as inputs and outputs every time I open a project.

In addition to that, only audio within a loop is played. If the loop is deactivated or the audio is outside the selected bars, playing it doesn`t produce any sound.

I use Cubase 10.0.30 Build 236 and the Focusrite Scarlett Solo interface.

I hope my description wasn´t too confusing. Does anyone have any idea what might be the problem?