Chat History Sync Issue

I posted this in Reddit a couple times hoping for some insight but received no response.

The issue is my chat/message history isn't consistent across all my devices. I have Gajim on three devices currently and when I go to a coffee shop or library and login with a laptop to catch-up on conversations, messages that have been sent to me earlier that day (or the previous many days) are not there. I am Archiving conversations and I have tried selecting "Synchronize History", but nothing is working. I have only one account and I'm logged into the same account on all devices. It seems like I'm missing something pretty basic, but I have no idea what it might be. Ideas?

PS - I'm on chatterboxtown.us