I, and a few others, are having a weird issue that only seems to affect some people, but not everyone. With a dedicated server, if running a custom map, some players will not be able to join and given the message that the server needs to be updated. However, others will join just fine and begin downloading the map. And yes, the server is fully updated.
This is where the issue seems to lie - downloading the custom map. We have not been able to pinpoint any one setting that may help, nor has completely redownloading the game.
However, if the player downloads the map from the Steam Workshop themselves (Subscribes to it), and restarts their game, then they are able to join just fine. That is, until another custom map is voted and they don't have it already downloaded. So there is a bit of a workaround if you know what maps to get ahead of time.
This is where the issue seems to lie - downloading the custom map. We have not been able to pinpoint any one setting that may help, nor has completely redownloading the game.
However, if the player downloads the map from the Steam Workshop themselves (Subscribes to it), and restarts their game, then they are able to join just fine. That is, until another custom map is voted and they don't have it already downloaded. So there is a bit of a workaround if you know what maps to get ahead of time.