Blackmagic Issue

Hello. I'd just bought a Ultrastudio Minirecorder. SDI In and Thunderbolt OUT to my Mac.
I'd installed all the drivers (10.7 Video Utility) .. but when I turn on the camera and open Media Express in Log and capture I can see the video, but sometime it just freeze. I close the app and reopen Media Express and it's a black window in Log and capture.

I open OBS to stream live, if I add a Blackmagic source, it can see the Ultrastudio mini recorder, but it is also a black screen, nothing appears.

What could be the problem?

Thank you

Late reply, but I've always had this issue with my miniRecorders, i now own two, and I bet it's this issue where they default to accepting the SDI input not the HDMI input. It's a total time waster for me and sometimes in the pressure of a live broadcast and the signal has dropped and caused the miniRecord to switch to SDI I mistakenly think my HDMI lead has failed or something else. Really annoying and can cost you a tonne of time when you dont have it.

The (temporary) fix is to open BlackMagic Desktop Video Setup (on macOS it's called that) either the app itself or via the System Preferences settings panel which causes it to open the BMD DV app and there you can see you BMD devices, and what settings they are on like input source (i.e. HDMI or SDI), framerate etc. Click on the icon in the middle of screen and you can change to HDMI from SDI.