Mini Monitor 4K & Premiere 12.x Footage Dropping Frames

I am editing footage from a Phantom 3 Pro quadcopter - 1080p 59.94.
The footage is jerky or stuttery when I play it in the source or program window. I know it's h.264 long gop but even if it's transcoded to DNxHD it still drops frames. I have a Samsung 950 NVME for program files and cache and my footage is on 2 internal drives in raid 0.

When I turn off Preferences->Playback->Blackmagic Playback, it stops stuttering.

Resolve plays the footage perfectly. VLC plays the individual clips perfectly. Premiere is the only program that has problems. I'd move to Resolve permanently but I use After Effects too much. I'm working on learning Resolve/Fusion.

Has anyone else experienced this? Know what settings I might change?
Thanks

For what it's worth, I figured out that my problems are between Premiere CC 12.X and my Mini Monitor 4K.
In Premiere when I go to Edit->Preferences->Playback and un-check Blackmagic Playback I get perfect playback in the GUI monitor. Every time I turn it back on Premiere drops a massive amount of frames regardless of transcoded codec. I have the latest Not sure why nor was Blackmagic Support. Real bummer...

UPDATE: If I choose Blackmagic Playback for Audio Device in Premiere the video plays perfectly on the external monitor? I don't get it?

Update02
That did not fix the problem. I continue to drop frames. It's actually worse If I choose Blackmagic Playback for Audio Device in Premiere. I'm now in Premiere 2019...