I thought it was my Samsung phone that wouldn't send or receive picture messages, however I bought a LG g4 and the problem still persists. This isn't just once every few months, it's more often than not that I can't send or receive pictures.
We have been working through a handful of picture messaging performance issues, and have identified a root cause. There are several platform upgrades scheduled over the coming weeks aimed at addressing this, and the most pertinent is scheduled near the end of this month. I expect the service will improve for you after it is complete, however, I'll follow up with you once it's done to make sure.