Some servers have very bad performance, to the point where playing games is impossible. The main problem is, when you switch to a game (or back to the lobby), the ground doesn't render for up to a minute, meaning you miss the start of games and are floating in the void.
This happens the most frequently on Lifeboat and Mineplex.
Thank you for your report!
However, this issue is Invalid.
Unfortunately we don't accept issues related to External Servers here on the bug tracker, but please add more details if you think this also affects multiplayer over Realms, LAN, or XBL.
I'd suggest contacting the server owner directly or seeking help on the Minecraft forums.
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