UltraStudio 4K / LG C8 issues

On a few recent projects that are on 29.97fps Resolve and Avid MC have issues connecting to the LG C8 display via UltraStudio 4K. It worked fine before I upgraded to High Sierra and the latest Desktop Video (10.11.4).

Going from MacPro 2013 to UltraStudio 4K, and from there to two monitors - LG C8 via HDMI and FSI via SDI. FSI monitor is always fine, C8 can get 23.978 signal but not 29.97 signal.

Interesting enough on Resolve if I briefly switch the monitoring settings to 23.978 the LG C8 catches the signal, and if I switch back to 29.97 afterwards it works fine. Like something has to be initialized or cleared out?

These are UHD timelines, so 2160p23.978 and 2160p29.97.

Anyone else seeing this or ideas?

I'm actually using an UltraStudio 4K and an LG C8 and have no problems. We're also on High Sierra 10.13.5.

I don't do 29.97 projects that often, but I do them occasionally and they work OK. Generally, I have to quit Resolve, refresh the monitor, then relaunch Resolve and bring up the other frame rate, and then it's fine.