Random models like Mal’Ganis are invisible and unselectable for me on Warcraft 3 Classic 2.0.1.22498. Sometimes I also have random invisible mobs with the same issue.
Reloading a savegame does nothing, but restarting the mission fixed it. When I loaded that borked savegame again Mal’Ganis was invisible again so the issue is reproducable at least.
https://i.imgur.com/FTcMDLs.jpeghttps://streamable.com/y7d3h4