iMessage History Not Loading

So recently I’ve been having a problem where iMessages won’t load my older messages (past about 6 days) when I scroll up. The loading icon appears, but the messages never actually load. The weird thing is this is only a problem with one specific contact.

I’m using an iPhone 11 Pro running iOS 13.4 (was having the problem before the update) and I honestly have no clue how to fix it.

I read through a few threads about people with similar issues, though most of them were from 2016, and regarding iPhone 6/6s models. Regardless I tried some suggestions I found there such as resetting all settings, and even resetting the phone and restoring from an iCloud backup. Nor was the problem fixed when the person messaged me again, despite another common suggestion I received.

I thought it may have been an issue with my messages saving to iCloud, but I’m not entirely sure how that works, or if that would even delete them from my phone. If this is the problem, it’d be great if someone could briefly explain how to retrieve the messages.

Also, when I go into the details tab I can see all the attachments from the messages that I’m unable to view.

Any help is much appreciated, thanks!