OT. Need some tech help

[dwrush22]

I tried to look online but can't find what I need. I have an iPhone 6s. So I am in a field where I'm involved in lots of group text threads. If it's all iMessages this works great. If someone isn't an iPhone user I go through periods where I don't get their text but they see mine. Then 3 days later I get all the text back to back from the last 3 days all at once. Plus I can be sitting next to someone else who is in the same thread, who has the same phone, and is on the same plan with me and they will be receiving the messages that I'm not. SMS and MMS are turned on in my settings. Not sure if that info is vital. Please help.

 

[PredVol]

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