My first suspicion is that you are testing this out on a local copy of the database, or is it on a server?
If its local, you need to “enforce consistent acl across all replicas” for it to work on a local copy - user roles don’t work on a local copy unless you have this enabled in the ACL.
You know, this sounds really familiar. I could have sworn I remembered this being a bug in some past version of Notes, but I can’t seem to find anything about it in the Fix List or the KBase now. (I might be remembering something from a long time ago, too - it all blends together after a while!)
Your post says you’re on 6.5.1 - any chance you can try upgrading to see if the problem resolves itself? If not, I’m not sure what else to try - I do the same thing in lots of my apps. (I’m on 6.5.3.)