Justin,
I am also using Panasonic AG HMC80 cameras with the ATEM 1 M/E and getting sporadic glitches, a few frames of black. Switcher is set on1080i with Four identical cameras, 50 foot HMDI cables. All from the same cable manufacturer. Some connections are worse than others. Is this the same problem you were getting when you ventured above 25′?
Solutions?
Thanks, Phil