Maybe the action that should run (after that when card) doesn’t work as expected? You could add a “Add to timeline card” on the error side and use the “error” tag to see what’s going on. You can add more of these cards (after each flow card) to have some kind of logging to see what’s going on.
That’s because you replace the actual trigger.
So, if the trigger is the problem, you’ll discover that’s the issue by test running the flows.
‘every 5 minutes’ or ‘20 minutes before sunrise’
both are flow triggers.
I’d like to suggest to report these issues to homey.app/support.
Possible fix:
Sometimes the internal clock is off. You can “force” it to the right time by navigating to More… > settings > location in the mobile app.
Now move the pointer on the location card to an other timezone. After a minute or so, move it back to Homey’s location. This should do the trick of resetting the internal clock.
Just make a simple time flow and see if that one works. In that case remove the time card from the flow and make a new identical one, to see if your problem is gone.