This issue appears to affect me and other hosts who use the mod AI Wave Survival. Don't know if it occurs for hosts using other mods too.
When hosting a game, and more than 1 observer joins, so that there are 2 or more observers when host launches game, when the dialogue asks to kick all observers, the host will then crash.
If a host tries to manually kick an observer by clicking on their name, and the observer is not removed, this is a guaranteed indicator that the host will crash when trying to launch.
Possible Fix:
- Enable "Allow Observers"
- Manually kick observers.
- Any observers who can't be kicked because of bug won't crash host, and also don't appear to load into game, causing no connection issues.
Hosted a game recently, had two AFK players, so moved them to observers. They still were AFK, so decided to launch. Manually tried to kick both observers, but was only able to remove one. The observer bug, that blocks hosts from kicking observers, would not allow me to remove them.
Decided to launch, even though I expected to crash. However, I happened to have "Allow Observers" enabled (usually I have it disabled). Instead of crashing on launch, the game played without issue.
As for the player who was an unkickable observer, I am not even sure they loaded (and if they didn't load/launch, it didn't cause game to lock up waiting for players on start). If they did, they remained an observer for the entire match, as they never DCed.