Normally, hitting 'start spectating' when you are in a room and both players start playing, it should just load the song and jump to wherever in the chart the players are, but in cases where the 'start spectating' button was not pressed while players were loading their files and begin playing, it will not load the song or go to multiplayer spectating.
Tried isolating the case myself and found issue with spectate button working between 2 of my alts starting a song in a room and viewing it as a spectator on 1.4.0, (alts ran flash projector .swf link)
Build 2020-06-14 1.4.0
Normally, hitting 'start spectating' when you are in a room and both players start playing, it should just load the song and jump to wherever in the chart the players are, but in cases where the 'start spectating' button was not pressed while players were loading their files and begin playing, it will not load the song or go to multiplayer spectating.
Tried isolating the case myself and found issue with spectate button working between 2 of my alts starting a song in a room and viewing it as a spectator on 1.4.0, (alts ran flash projector .swf link)