Odd, since I have not seen any problems with either sending or receiving MMS'es, and I use MMS a lot.

Do your problems relate to sending or receiving?
Have you checked what's in the journal when you have problems, and compared to cases when it works OK?
Does SMS work correctly to you?

My network setting is "prefer 4G" but I have to confess I have not checked on which network my device is anchored to when sending MMS messages.