Multiview on my ATEM 2 M/E flickers whenever tally fires — 25 minutes to doors in a 600-cap ballroom. I’ve got a Decimator MD-HX, spare SDI, and a small UPS; would you re-clock the multiview out first or reroute to an aux and isolate power to lock it down?
Re-clock the MV through the MD-HX and force 3G Level A/auto with output locked to your ATEM standard; it’s the quickest save with ‘25 minutes to doors’… If it still flashes on tally, swap the SDI and put the monitor + MD-HX on the small UPS to rule out a power burp — what format are you running — 1080i or 1080p and Level A/B?
I’d throw the MD-HX on the MV out, hard-lock it to your ATEM format, and power the MD-HX plus the monitor from the UPS — little seatbelt for the multiview. Small caveat: aux won’t carry multiview on the 2 M/E anyway, so if it still blips try the second MV port or a fresh SDI. @nash_jones87 is right on the lock; does it flicker on both MV outs?