Powershell monitor stuck in "Initial poll in progress"

I have created a new powershell monitor template which runs fine when tested. Assigned to a node it is stuck with the "initial poll in progress" message.

I have deleted the monitor and reassigned it, run "poll now", unmanaged and remanaged and restarted the "Solarwinds Orion Module Engine" service. Nothing helps.

I can see the that the monitor actually runs as the "next poll time" is updated (runs every minute) and also a file is updated everytime the monitor runs.

What am I missing?