App Group Claim with custom name

I’m trying to create an App level group claim with a custom name, but it is not coming across in my ID Token’s claims. Here is what I’ve configured:

So I’m expecting a claim in my ID token called “thisApps_groups” that has all my groups (I’ll filter this later), but I’m not getting one. My ID Token only contains the following:

claims

I’ve set up groups as a custom claim with the same regex filter. This way I can have a global “groups” claim included if the associated scope is specified, otherwise I’ll only get the groups associated with the App I’m authenticating to. What am I doing wrong or misunderstanding where I’m not getting the “thisApps_groups” claim back?