Rando10 I definitely searched for it before posting, but maybe I just didn't use the right keywords or overlooked it.
I think you would be forgiven for not having been able to fully navigate the forum's search feature; in my view, it's not the pinnacle of forum search software in terms being able to present relevant search results.
I found a conversation from yesterday in the chat rooms which suggested that there's a known issue with sending/receiving SMS to/from group chats. Is this what you're seeing? In the chat, a GrapheneOS developer suggested to try resetting cellular settings by going to Settings > System > Reset > cellular settings reset.