Black screen with ATEM Mini PRO ISO and 25m 4k HDMI cable

ATEM Mini PRO ISO detects no signal when connected through 4K@60Hz 25m fiber optic (with Ether.) HDMI 2.0 cable.

If I connect the cable directly to a display monitor - it displays image correctly.

Setup:
Sony A6400 -> 3m micro HDMI to HDMI cable (2.0) -> F-F HDMI connector (passive) -> 4K@60Hz 25m HDMI 2.0 Cable

Alternative setup (Same result - no signal):
Sony A6400 -> 3m micro HDMI to HDMI cable (2.0) -> Atomos Ninja V recorder (active) -> 4K@60Hz 25m HDMI 2.0 Cable

When I say no signal = Black screen. I did not find any settings/indication in the Control Panel where I could differentiate between no signal & black screen.

What are the requirements for the cable? Any ideas why this setup doesn't work?

Copper cables over 7.5m may not work with any ATEM switcher. That includes the ATEM Mini, TVS HD, 4K etc

Sometimes if you route the longer cable through a splitter/repeater/loop thru device etc they may work with an ATEM.

Fiber cables of any length work fine with all ATEMs.

I updated the description. The 25m cable is fiber optic.

It turned out to be a faulty cable. It worked for everything but ATEM Mini. I bought the same cable and it worked.