UltraStudio Mini + RX100 black screen

My problem is I'm getting a black screen in Blackmagic Media Express from my Sony RX100 VA, plugged in via HDMI through a UltraStudio Mini Recorder.

I've happily streamed video from a Sony a6500 over HDMI through the UltraStudio. I'm guessing I have the settings setup incorrectly, but I don't know what the right settings are. I've tried changing the Project Video Format in Media Express to match the input stream, which I thought was 1080i60 from looking at the HDMI output settings in the camera.

There is a white light on the UltraStudio indicating a connection, and my MacBook can see the UltraStudio.

Can someone help?

I plugged the RX100 into my computer monitor and hit the info button on the monitor. It lists the input as 1080i. In the HDMI Output settings of the camera I set the output to 1080i 60p, and in Media Express also to 1080i60. Still a black screen.

After all that, unplugging and replugging the HDMI to the RX100 triggered an automatic setting change in Media Express to 1920x1080i59.94, which is displaying video now! Odd but glad it's working.

Okay I've found the trick to this is turning the RX100 VA off and on. The video pipes through successfully after turning the camera back on. My HDMI Resolution is 1080i and 24p/60p Output setting is set to 60p.

Another trick to getting clean HDMI output is Menu > Setup2 > HDMI Settings > HDMI Info. Display > Off.

Sometimes I get video through HDMI at these settings. Sometimes not. It's random? Sometimes it seems changing the recording medium to AVCHD helps... but why? Then sometimes it doesn't help.

This doesn't seem like a very reliable camera for HDMI output, unless my UltraStudio Mini is at fault...?