ATEM mini iso CAM1 working CAM2-4 not

I have an atem mini ISO version 9.5.1 and when I plug my camera into the CAM 1 it works, but if I plug the same camera into CAM 2, CAM 3, or CAM 4, I am getting no signal.

But when I plug it back into CAM 1 it works again. I checked the settings to make sure the cameras were disabled in some way but did not find anything.

Any suggestions?

Two things that will help others answer.

1. What is the camera resolution, frame rate and type i.e progressive or interlaced.
2. How long is your HDMI cable?

Reportedly, Input 1 has additional input capapability compared to Inputs 2-4, but hands-up, I'm not an expert in that area.

HDMI input 1 on 4-input Atem Mini models, and HDMI inputs 1 & 2 on 8-input Atem Mini models accept both RGB and YCbCr (4:4:4 and 4:2:2?) format HDMI inputs, whereas I believe HDMI inputs 2-4 and 3-8 respectively are more limited in HDMI format support and only accept YCbCr (4:2:2?) HDMI sources?

If your camera is outputting RGB (and possibly YCbCr 4:4:4) it may be limited to which inputs it can connect to. if you can't force your camera to HDMI YCbCr 4:2:2 output then Decimator MD-LX devices allow you to convert RGB to YCbCr 4:2:2 and so may be a solution for input conversion. (Although they are bi-directional converters they will function as HDMI to HDMI format converters if you configure them to do so)