I had this same problem the last few (?) weeks. Going through the MANY steps in Verizon's online troubleshooting, the step that finally worked was finding that I had a block turned ON, specifically the "Block Picture & Video Messaging". It's a mystery how this block got turned on....
Using My Verizon app:
then hit "Manage" under your phone number
at top of screen, choose "Controls"
hit "Adjust service blocks", check that Block Picture & Video Messaging is OFF (mine was ON for some mysterious reason - once I turned it OFF, I was good to go with sending/receiving texts with my Android group or mixed Android/iPhone groups!
tmwimmer, staying connected with your group message is always important. Are all the devices within the group message Apple devices? Is Send as SMS enabled on each one? Normally, Android devices can't send or recieve iMessages so having these options can help with this.
Follow us on Twitter @VZWSupport
If my response answered your question, please click the "Correct Answer" button under my response. This ensures that others can benefit from our conversation. Thanks in advanced for your help with this!