Discovered today that GrapheneOS (and its native apps) will not update when a VPN is in place on the phone. Aurora Store and F-Droid will update, but Graphene system updates and default app store don't work over the VPN.

Had been wondering why I hadn't received updates in recent weeks to the core OS, but most apps were updating successfully. Disabled the VPN temporarily and GrapheneOS updated itself, then re-enabled the VPN.