Dota keeps kicking me back to lobby unless I use "Local Host"

[leaden nest]

I just got my mod uploaded to the workshop with visibility set to only be Friends.

I make a lobby
Hit start game
accept the match
it says finding server...

and then I get put back in the lobby after 1-11 seconds.

However, if I use the "Create Custom Lobby" menu to set the server to "Local Host" the mod launches fine.

Not sure what is causing this, or how to debug.

[languid yacht]

You can use valve servers only for public mods