Had the same issue yesterday. Even tried using 3rd party apps. Eventually I did the usual, rebooted the device. After I did this, everything was back to working normal. Been switching between Handcent SMS and Textra... BTW, make sure group conversations is checked, under the MMS settings on stock messaging app. Hope this helps..
Don't fret. We'll get you back in the loop with group texting so you don't feel left out. First, I have to ask a few questions. Are you receiving any error messages? For now, please go to settings > application manager > all > messaging > clear data. Next, please go to your texting app, select the bottom left menu button, and make sure Group conversations is checked. Then clear out your texts messages, test, and update us.
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