Just want to throw some other hardware solutions out there for easily getting OSX to speak in compatible frame rates to the ATEMs...
I have a ATEM Production Studio 4k, and use a 1 M/E 4k at work a lot too.
For 1080p... Decimator MD-HX or MD-CROSS is definitely a handy thing to have in your kit. Decimators are bombproof! I've had one running at home for 2 years, the LCD is gonna give out before the unit does. The AJA ROI's also do the trick. Both of those are relatively high ticket items, but cheaper than ImagePros or Extron USPs.
But I just stumbled onto an interesting
MEGA CHEAP hardware solution for 1080p59.94 while testing my rack that is about to go out on a rental. I picked up a handful of VGA->HDMI (semi-generic) converters on ebay a while back, I thought I'd give one a shot. Voila!
So.
MiniDisplayPort/Thunderbolt/USB-C -> VGA -> El Cheapo VGA/HDMI Box -> HDMI Input on ATEMThis test case was High Sierra outputting via mini-DP (generic mono-price adapter).
By El Cheapo I am referring to this one, although you may have luck with other's in the same price range or re-brands of this one:
Etekcity VGA+Audio to HDMI converter/scaler
- Etekcity VGA+Audio to HDMI Converter
- Screen Shot 2019-02-07 at 12.37.27 AM.png (241.71 KiB) Viewed 5146 times
...no longer available on amazon, but there are on ebay for 25$ or less. I got 16 of them for 34$ last year! By no means a robust or elegant solution, but budget might be your constraint? Hobby streamer maybe?
Also might have the side benefit of avoiding HDCP issues, (have not tested this).
For Mac uses cases, those HDMI inputs are useful again without having to fight with SwitchResX, which is never an option on a client laptop! (Decimators also let you do this, if you scale HDMI->HDMI, but at the 300$ price point).
Cheers!
Ryan