Resolve Delta Keyer leaving black splotches

[Forrest Kos]

Hello,

 

I'm using Resolve 18 to key some Canon Raw green screen footage. Everything goes relatively smoothly until I adjust the Matte threshold. The Alpha channel looks pure white, but the footage gets black splotchy / grainy. I can't find any work arounds to get rid of this. I believe my footage is exposed well. I tried a quick Colorspace transforms (guessing settings) in my node tree to see if more saturated footage would help, but it did not.

I tried as many different workflow attempts as I could find. I used a clean plate as the keyer color, and the footage still gets the black dots. When changing view mode to intermediate result it did seem to get rid of the black dots but the green background came back at half transparency, so I assumed it wasn't working?

I also tried the 3d Keyer and got a nice result with no grain, but the mask had a green outline.  Is this a better keyer than the delta?