mms not sending

Are the images too large to send?  There was a bug in a few of the betas that kept popping up that the file had to be less than 1.05MB.  It was only when you used the picture button and not using the + sign.  I don't know if that issue ever made it into a final build as I only have the latest beta builds.  You could also try a different text app, like Textra, to see if the issue happens with their app as well.