Double Firing cron Rules in OH3

Hi everybody,

I migrated from OH 2.5.11 to OH 3.0.0 one week ago.
Everything working fine so far.
But today I had the issue that some (and not all) of my cron rules are firing double:
Here’s an example of one of the cron rules:
rule “Buerotemperatur auf normale Temperatur morgens abhaengig von Praesenz”
Time cron “0 5 6 ? * SUN,MON,TUE,WED,THU,FRI,SAT”

In the event.log I can see, that the rule was firing one minute to early (6:04) and again at the correct time (6:05):
2021-01-05 06:04:02.466 [INFO ] [openhab.event.ItemCommandEvent ] - Item ‘i_mqtt_thermostat8_Targettemperature’ received command 23.0
2021-01-05 06:04:02.479 [INFO ] [penhab.event.ItemStatePredictedEvent] - Item ‘i_mqtt_thermostat8_Targettemperature’ predicted to become 23.0
2021-01-05 06:04:02.482 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item ‘i_mqtt_thermostat8_Targettemperature’ changed from 20.0 to 23.0
2021-01-05 06:05:00.457 [INFO ] [openhab.event.ItemCommandEvent ] - Item ‘i_mqtt_thermostat8_Targettemperature’ received command 23.0
2021-01-05 06:05:00.458 [INFO ] [penhab.event.ItemStatePredictedEvent] - Item ‘i_mqtt_thermostat8_Targettemperature’ predicted to become 23.0

The rule was working fine in version 2.5.x for over an year and in OH 3.0.0 for more than a week. Other cron rules are firing once only
Time on the Raspberry Pi (where OH is running) is ntp synchronized.

Any Idea, what can go wrong here?

First of all, please use the code fences (``` before and after your code), makes it better readable.
Then, please tell us, what your rule does exactly and what you’re looking for expected behaviour. Adding your item “i_mqtt_thermostat8_Targettemperature” would also help.

Oh, and just to be sure, try to “log_info()” something in your rule, so you’re really sure, the 06:04:02.466 came from your rule, sounds either you pressed the play button on your rule or the item was updated outside of rule context.