HI @saalfsef,
Could you please share a bit more about the error message on your side?
I have made a test on my side and the flow works well. My flow's configuration as below:
The flow works successfully as below:
In addition, the "Start Flow" action of Flow management connector is used to enable the specific flow rather than excute the specific flow. In other words, when a flow is disabled, we could use "Start Flow" action to enable the flow.
If there is something error with your "Start Flow" action, please check if you are the Environemnt admin of your Microsoft Flow. It means that you should create a connection to Flow management connector with a account which has a Environment admin permission.
More details about the Flow management connector, please check the following article:
https://flow.microsoft.com/en-us/blog/planner-triggers-connector-improvements/
Best regards,
Kris