Systemd Service Summary: Service 'apt-daily' activating for: 12 hours

CMK version: 2.4.0p22
OS version: Ubuntu 24.04

Error message: Service ‘apt-daily’ activating for: 12 hours

Recently we see some Checkmk agents showing apt-daily or apt-daily-upgrade as “activating” für 12+ hours. This is surprising because it should aldready alert after 10 minutes. So there is a huge gap from the standpoint of the reaction time

This looks like a false positive. Especially when we look at the system itself:

Service alert	2026-03-19 12:01:14	SERVICE ALERT	HARD (OK)	Total: 142, Disabled: 8, Failed: 0
Core produced a notification
Service alert	2026-03-19 12:00:12	SERVICE ALERT	HARD (CRITICAL)	Total: 142, Disabled: 8, Failed: 0, Service 'apt-daily' activating for: 12 hours 0 minutes (warn/crit at 5 minutes 0 seconds/10 minutes 0 seconds)CRIT

And from the system log

Mar 18 23:11:46 demo.example.com systemd[1]: Finished Daily apt download activities.
Mar 19 12:00:12 demo.example.com systemd[1]: Starting Daily apt download activities...
Mar 19 12:00:12 demo.example.com systemd[1]: apt-daily.service: Deactivated successfully.
Mar 19 12:00:12 demo.example.com systemd[1]: Finished Daily apt download activities.

Any ideas what is happening there?