Received iMessages deleted from only 1 contact
My iPhone appears to be deleting iMessages I have received from only one contact at random times. I have watched it happen. It deletes the last ~10 messages that person sent me, but retains everything I have sent in the message window. When photo messages are deleted in this process, they still remain in the "info" section of the conversation. The other person can still see all of the messages (both mine and his) in the chat window.
This doesn't appear to happen with any other contacts. I have tried turning iMessage and MMS on and off in Settings. I have restarted my phone. I am using iOS 14.4 on an iPhone XR.
iPhone XR, iOS 14