OS? I'm assuming the purple stuff in the foreground is the mess that's being created. Your clip is awfully contrasty..
From a screenshot of your screenshot with all modified properties revealed. Just used the Select, Clean BG, Clean FG buttons. OS X 10.11.6, Mac Pro, AE CC 2017 22.214.171.124, Primate 5.1.3:
Pressed the U key twice to reveal all modified properties...
The look of the image is after I select the green. The original looks like this.
I am using windows 8.1, I have been using Primatte keyer for a few years, i only got these issues after the update.
when i use the select Background this is what i get
It samples a greyish instead of the green.
When i use the sample tool this is what i get
But once i try to use the Clean FG it messes up and goes crazy like the second pic.
I will contact Red Giant, I do not have an older version at the moment.
Thank you very much!
I solve my problem updating to windows 10.
It worked perfectly!