Basically, when using the electric cloud chest in multiplayer with my friend, we noticed that random items get deleted, at first we thought this was because we added too much storage, so we tried in another colored chest with less storage, but items still randomly disappear

This isn't just in Multiplayer. I've been dealing with issues like this in singleplayer too. Mostly small things, like a handful of concrete blocks, but yeah. I've also had issues with duping, such as a stack of anvils always being refilled no matter how many I took from the stack.