Intersection Security Group in proxy policy

Hello,

Looking for some ideas on how I can set up proxy for a group of workers who should only be able to proxy on behalf of workers in an intersection security group. The intersection consists of 2 unconstrained organization membership groups:

1. Workers in X cost center hierarchy (current org and all subordinates)

2. Workers in Y location hierarchy (current org and all subordinates).

I created an intersection security group with these 2 groups but I can't seem to add this intersection to our existing proxy policy. Are we not able to use this security group type in a proxy access policy?

Any ideas on how I can accomplish this? TY!