Can't Recieve Some Members in Group Text

I have recently moved to T-Mobile from PagePlus. I changed from an Iphone to Android. I have kept my old number. Some users in a group text I can recieve but others I cannot. But, I can text those that I cannot recieve in the group text individual and get replies from the with no problem. I purchased a new Moto G stylus 5G kit that came with a T-Mobile kit. 

Thanks for any assistance.