I have a 42 person group that I send mass texts to for invitation purposes, and as of Beta 4, when I go into that thread, it claims it's an iMessage, and will not send anything. The send button is blue, but "greyed out" so to speak, such that when I type in it, I can't send. Anyone know if this is a beta 4 issue, or why I'm not able to send a message to a group?