Hanging jobs via scheduler

Product: PowerShell Universal
Version: 4.2.18

From out of 30 scheduled scripts I have a handful that get stuck nearly on a daily base. It is simple scripts that normally complete within 2-3 seconds. but often in the morning i do find them in the state of running since 7 hours and never finish. other instances of the same scheduler are therefore also not started.

the only thing that is a bit different for them compared to the rest of the scripts that they run quite often, most of them every 5 minutes.
the jobs that get stuck are always the ones shortly before midnight.

As our PS Universal installation was still the one from the trial where we only tested the free license, it reinstalled a complete fresh version of it. The old does use IIS hosting, the new directly the PS Universal server. the issue is on both installations.

the timeout for the script is set to 2 minutes, both in the script and also in the scheduler.

some advice would be much appreciated.