Cannot see latest iMessages

First, story time: Earlier today, I saw a few messages pop up in one of my group chats. Later, when I opened iMessage, those messages were gone. All I could see were older messages from weeks ago. The latest ones just disappeared. I tried restarting my phone, hoping that might fix it, but no luck. The new messages still won’t load.

Secondly, to make things even more frustrating, there’s a syncing issue between my iPhone and my MacBook Pro. Sometimes I’ll receive new messages on my phone, but when I check iMessage on my computer, those messages are nowhere to be found. It’s like my devices are living in two parallel universes.

What is going wrong?