Resolve 12 - 0 FPS playback color page

I have just installed Resolve 12 and everything has been working well with the exception of playback in the color page. I am getting nice smooth playback on any other page including edit but on the color page when I hit play it shows a green 0 FPS and never begins playback, if I switch back to edit I can playback realtime with the grade showing. Any ideas?

[Dwaine Maggart]

As a test, if you have a Capture/Playback device configured in Resolve Preferences - Video I/O and GPU area, set that to None, save the prefs and restart Resolve and see if that made any change.

If it's already set to None, do a prefs save and Resolve restart anyway, and see if that has any effect.

Was already set to none, did a pref save and no change.

What's the hardware? What kind of GPU? What operating system? What's the hard drive source?

It's possible there may be some other non-obvious speed hiccup here. My Mac is running 10% hotter than v11, but it's playing R3D 4K clips at speed (half-res good) in HD and rendering fine. (So far.)