Hi Lukas,
my guess would be that this is one of two issues:
Either the updates did not all install properly - this sometimes happens. We’re not quite sure why. The best things is to run the update installation again from the command line (bin/update) until it tells you that all the updates have been applied. Then try restarting the program.
Alternatively, could it be to do with the Ubuntu version you are using? Over the past couple of months we had issues for a few people on the newer versions of Ubuntu, so we now have Versions for 16.04, 20.04 and 22.04. If you were originally using the 16.04 build, then perhaps switching to the 22.04 build might solve some issues for you. You can download these on our downloads page Software Downloads - CCPN.
Vicky