FWIW, I have had the same issue once. Snap 5x1, 35ft HDMI cable, Directv, Samsung Bluray, Appletv, Firestick going to an older Samsung LCD tv.
Everything but Appletv passed fine. Setting ATV output resolution to 720p cured it.

Just wanted to throw my experience in here to show that this isn't a one off event, there are some weird issues with Snap HDMI switches and Appletvs.

I have used several Snap HDMI matrix switches and never experienced this issue with those, it appears to be unique to the 3x1 and 5x1 HDMI switches.

I've had a few issues over the years: two power supplies for DVRs, some wattbox issues when the first come out. some cams go bad. but really, thats about it. Oh, one sub amp. But havnet done many Snap amps. Cant say its any more than any other manufacturer. Keep in mind Snap manufacturers MANY products so a fair comparison would have to be between multiple vendors issues vs. Snap.

Using a 5x1 with 3rd gen appletv, directv, BluRay with no issues. I do set a weekly power reset of the binary switch via WattBox though. Haven't had an hdmi related issue on that job yet. Granted the appletv is 720 though

I stuck a 5X1 on Friday, VCR/DVD combo player on port 1, port 2 open, Bluray on 3, appletv on 4 and dish network on 5. All seemed to work thenbut this is also a possessed house. So we will see if there are any messages in the morning. This house always has an issue....be the stucco failing, windows loosing the seals and fogging, lighting processors failing, bats in the attic, elevator motor failing, always an issue somewhere. We recently redid the theater and all was working well and then the dvdo failed so the 5x1 went in.