I have tested my cables first with atem 1.
My long cables working ok (max 15 meters).
I used sony V1 for tests and dell notebook with hdmi.
And when my new ATEM TVS arrived
I make test again on TVS and long cables NOT!!! working.
I used 1.4 hdmi AWG 24 spec. 10 meters and 15 meters.
Yes in meters I am form Poland 🙂
Something wrong with TVS?