Having a really bizarre situation with multiplayer world

My project is fairly simple. The host can create (either solo or during multiplay) a tiled grid system, and change the tiles or place items on them. It’s basically a virtual tabletop simulator. Everything works for the most part.

However, for some reason when a client is connected, sometimes (it can happen every five minutes or not at all for five hours) a chunk of the tiles will just fall into space. It’s like they unload, but they actually fall into the abyss. Which is weird, given they don’t have physics or gravity enabled.

This only happens client-side, and when the client leaves and rejoins the map, it’s back to normal. Guessing it’s because of packet loss or something with the connection flickering.

I am totally puzzled and I don’t even know where to begin with trying to figure this out.

Using 5.2.1, I have two plugins; Rama Save System (which only affects the host) and Advanced Sessions for the multiplayer connection.