UnrealInsights.exe gathers no data

Trying to profile with the new UnrealInsight tool. It connects to a session and seems to record, but when I look at the data everything is empty. No tracks in the main window, and timers all saying 0:

I’ve tried with both the release engine and a source build. Is there another step to enable debug data?

Launch the engine with -cpuprofilertrace -statnamedevents

thanks for that. I can’t find any mention of this in the manual, is there a list of these commands somewhere? I now have CPU stats showing, is there a switch for GPU data too?