i am having the same issue as the OP.
in the 2 weeks i have had the phone, i have only be able to receive 2 MMS messages from my wife out of 15+ attempts.
thought it might be her crappy LG G2X, but it wasnt. i tried to send myself a MMS and it wouldnt send.
i have tried changing some of the APN settings, and NOTHING has worked.
I have tried other MMS/SMS apps and none of them are able to send or receive a MMS
i am on Tmobile $30 plan and have NEVER had an issue sending or receiving MMS's on ANY phone i have had and i am a phone whore, no really, i have a new/different phone every month (i like my precious') while i have been waiting for the N5 to come out.