strict-marsh This is feeling like a Graphene issue.
It's not. It's related to Android 15 and the fact that it's an AOSP messaging app that is no longer supported. I ran into the exact same issue using a secondary profile. None of my messages went through even though the Owner profile would show as if my messages went through. Ultimately, I just stuck to only using the Owner profile, not touching any Permissions including Sensors and my messages started sending and receiving again.