This sounds like ancient history but years ago I had the very same problem. I had purchased the Outlaw 950 and had handshake issues for the video signal going to my overhead projector. The 950 was simply passing through the video signal which I assume the 976 does. A call to Outlaw revealed that the problem was the length of the hdmi cable and Outlaw's suggestion was anything over 15 feet was problematical. The distance from the Outlaw to the projector required a 35 foot hdmi cable, well above the 15 foot limit.

I realized the true distance the video signal was traveling including the 3 foot hdmi cable from the source (a bluray dvd player) plus the 35 foot cable. Did the pass through part through the 950 also "add" distance? My solution was to bypass the 950 altogether (buying a bluray player that had 2 hdmi outputs) with one going directly to the projector for video and the second to the 950 for sound. I also purchased a "redmere" 35 foot hdmi cable that boosted the signal. Problem solved.

In your particular case what is the length the signal travels and what is the quality of the hdmi cable which now has to handle 4K and HDR.

John