iMessage not loading messages between yesterday and a far previous date

My iMessage is not loading any messages between yesterday and Sept 10th. It stays only a day behind, so itll always show "Yesterday's" messages, but wont load anything between the day prior and Sept 10th. To clarify that further, if today is 11/26 it shows 11/25's messages, but nothing from 9/10-11/24, and yesterday it showed 11/25 and 11/24's messages, but nothing prior, etc and so on. It is only on one person's messages, and sometimes when I restart my phone it will come back up. I have my phone set to save all messages and never delete them, and I have more than enough room (presently 135GB free). This has been happening since iOS 15 very roughly, and I just updated to iOS 18.1.1, so it is not isolated to a specific OS version.