That is why I suggested the OP check whether the email addresses at which they could be reached were listed.Ah. If that's the case, then all I can think of is the phone is only receiving iMessages that are sent to phone number only and people are sending some iMessages to the email address and since the phone isn't set up to receive both, only gets them when message is sent to the number.
OK I'll give that a try and see what happens.View attachment 32535
The iMessage (top choice) has to be turned on (green) or you have what you have. If it is green, turn it off and turn it back on again.