I get that prompt every time I start a convo by sending an iMessage effect. It’s a bug. Doesn’t have anything to do with SIMs or contact cards or anything.
That happens any time you try to *BEGIN* a conversation with an iMessage effect.
You can reproduce this by *STARTING* a convo with someone that you don’t have an active message thread with.
If you already have a conversation thread with someone in your Messages app list, it won’t work. But starting a conversation with someone you don’t already have a thread with by using an iMessage effect will reproduce this bug every time.
I’ve reported this to Apple multiple times but have finally given up.