Phone changes known senders to unknown

Sometimes when receiving a text from known senders (friends in my contacts) the text arrives with bubble empty instead of initials (first photo below). Then when opening text, the sender name gets changed to unknown at top, names are still noted over individual responses in group. . When unknown is at top, instead of group member names, it’s like my text is locked and I cannot send response. (Second photo below)Usually only happens in group text. I have to start whole new text to group to be able to send response. Nothing can be done with original text. This just started happening and just randomly occurs. I have newiPhone 7s but my friend also had this happening on 5s. Anyone else have issue and know of fix?