I don't suspect this is an Android specific problem, but I don't think there's another more relevant Stack Exchange.
I switched my carrier from Verzion to Google Fi and took my phone number with me, new SIM card. Ever since the move, for one specific contact I don't receive MMS messages (group chats or photos) from them. I can receive SMS/texts from them no problem. I can receive MMS from every other number (that I'm aware of) no problem as well.
Does anyone have any ideas why this would be the case? Sender uses Android as do I. They are not on Google Fi, I think T-Mobile.