Basic Machine Cert inspection in APM Policy

Yep, I know what you mean (I think) but apologies I think my terminology is wrong.

I have a list of certs, and some are external CA's which aren't we want to use. I had to "chain" some external certs for a different purpose. In this instance I only need to verify against an internal CA, which I have the certificate for on the appliance.

The issue is that when I select any certificate in this list, the selection won't stick.

Here is a screenshot of what I'm trying to change (had to black out some info that made me identifiable as I can't upload for some reason)

Screenshot