Lunar Client has a tendency to break on LEM a lot. It has reached a point where the game is unplayable, and here we have a list of everything it breaks.
1 - In the host menu, the chat and most Vanilla UI elements is not visible, and it is only possible to start the game with /trigger lem.gamecfg at this point.
2 - Commonly, all entities (Players, Chests, Armor Stands, etc.) fail to render, making them invisible. This makes the game essentially unplayable at this state.
3 - Many UI elements that use the bossbar to render break, such as the battle banner and panorama.
While you can’t play with Lunar Client, you can see our list of compatible Modpacks here