Tojo72
Interesting,they seem to be Sherwin Williams house paint,never used them for modeling no less an airbrush.
Actually that's wrong,I couldn't find anything on them
Zero Paints is a reputable company that mixes custom 'factory' colors for car modelers, mostly.
https://www.zero-paints.com/search?q=racing+point
Their website is kind of fun, check it out if you feel like it.
Back to the OP, I know of a member here who has used these paints, but unknown if he's tried to shoot the filler-primer and certainly not through the a/b you are using. Hopefully he will see this and chime in.
My grumpy old man sense tells me what you are trying to do isn't such a good idea (shooting a 'filling' primer through a relatively unknown a/b and the smallest needle/nozzle mentioned by the paint manufacturer.
That said, everything I just read on both the Airgunner and Zero sites says it should work. All I can come up with is make sure the primer is properly stirred, making sure the a/b is set to max power (Airgunner claims 25 PSI), and don't baby the double-action trigger, pull it back all the way. Zero actually recommends against further thinning, which you probably already read...sounds like you've done your homework.
I'd just try another primer if I were you. Zero doesn't care what primer you use, and were it me in your spot, I'd go get a can of Tamiya Surface primer in a rattlecan and get er done. Or if you've shot Stynlyrez with your a/b, that's be fine. Etc.
Have you tried to paint your Zero Color coat through your a/b yet? If that doesn't work, then I'd say it's something with the a/b.
This is a lot of stuff from a guy with no hands-on experience with Zero. Had some thoughts, thought I'd give it a go. Hope that's ok.