Power Management not working anymore

Hi there,

running ubuntu 18.04.04 with all updates applied.
Since some days power management does not work anymore.

The screen should turn black after 10 minutes and the system should hibernate after 60 minutes. Both things do not happen anymore. Screens stays active and also the system does not hibernate.
Edit: Windows Manager is Kwin

Since I never had any issues with power management, I have no idea how to debug this, so any help is appreciated :-)

Cheers, Rainer

PS: The search function in this forum returned a database error.

Seems to solved.
What I did:
- Reboot -> Did not help
- Switch power settings off and on again -> did not help
- Set other times to when it should hibernate -> did not help
- Reset settings to default and set new values -> did help