ATEM Mini ISO Pro - dead input?

So I cannot get the Input 2 on my Mini ISO Pro to work at all. Doesn't matter what I plug into it - I can swap the same cable/source over to any other input and it works fine.

This seems to be a common issue with these things. I know it's not my HDMI cable or cam settings, since the exact same source will work on other outputs. My firmware is completely up to date.

Is there any hope?