Can't interact with debian HVM


I noticed, that I can’t interact with one of my HVM’s via qubes anymore. I am not longer able to start software via the launcher or qvm-run. The problem is not limited to gui, qvm--run --pass-io <vm-name> "/bin/sh" does not work either. What I can do is changing the power state through qvm-start or qvm-shutdown, etc.
When attaching a serial console to the running HVM i am able to login correctly, so the VM seems to boot in a valid state.
I don’t know if the problems started after updating via the qubes updater, but it is possible. A week ago everything worked fine. The HVM was created from the qubes debian 10 template.

How do I debug this?

If you try the following, do you get a (promptless) shell?

qvm-run --pass-io --no-gui <vm-name> /bin/sh

If so, does anything stand out in:

sudo systemctl status qubes-gui-agent

after you’re in the qube shell?