With patch V1.31 for Warcraft 3, Blizzard added the capability for map makers to modify the in-game UI by code. With this feature, one can also create their own custom UI elements. These UI elements are called Frames.
Unfortunately, Advanced Observer Mode is totally broken if you use custom Frames in the custom map and try to watch a replay in this configuration. For example, a player’s starting unit, such as the main building, does nothing and doesn’t hire units. Units placed on the map can’t harvest forests; they just move around, and the fog of war doesn’t open because players don’t have any units at all. In the classic mode of replay watching, everything works as it should and is totally fine.