Hi! Could you explain the issue a bit more?

What “stuff” did you add to your levels that disappeared?

I've only known Factory 3 and Factory 4 to have the same issue.

High ping tends to be the source of this problem, most maps work, others bug out and will entirely disappear. The desync is quite noticeable when some of the players still hang in the air unstably. The host usually won't have this problem, to them, some players are falling through the map. As in, the map works fine for the host and maybe someone else, but for to everyone else, it's broken.

_Reducing ping_ and hosting / participating in a private match will improve results.

Set the Lobby room lever to "no" to set as private.


https://us.norton.com/internetsecurity-how-to-how-to-lower-ping.html

This link goes over some ping reduction measures you can take.

Well... the link went over:

1. Close programs and apps you aren't using
2. Temporarily disabling updates
3. Use an ethernet cord
4. Remove other devices from your network
5. Check the game server's ping
6. Select a game server closest to you
7. Adjust your frame rate
8. Upgrade your router
9. Contact your internet service provider
(You can also change your wifi to one that has a higher bitrate)

It was fixed a day after i reported it, that was 3 years ago, Sorry.