Why can I not send or receive MMS messages (pictures) to a couple of specific phone numbers?

Starting in the last week, I cannot send or receive MMS messages (pictures) to a couple of specific phone numbers. A week ago I could. I can still send and receive MMS messages to other numbers. The numbers that I have a problem with are not having problems sending and receiving MMS messages. I have restarted the phone using the volume down and power buttons and reset the network connections. 

Samsung Galaxy Note 20 ultra