On the web app (I don't know yet if it also happens on mobile), I can click on an enemy fleet and use the quick-menu to give it an order. I get an error message like I would expect, "you cannot change the queue of an entity that is not yours", but the problem is that the client still draws the order on my screen as if it was successful.
So I can grab an enemy fleet and set a course across the sector, put a giant red line through everything. It won't really go there since I can't actually change its queue, but now my game client is out of sync with the server. I can't fix it by just doing a request game update, otherwise I might not have even posted the problem. I have to close the client and re-open it to get back in sync, and that's the real issue.