if you're having issues with joining lobbies, please follow these instructions:
Right click Shift at Midnight in your library > Properties > Game Versions & Betas
and enter the access code:
networkissues
click opt into "network-issues-patch" branch this should update your game, and you should be able to join your friends.
Everyone you play with must also follow these instructions
We are working towards creating a proper fix in the main version of the game, but for the time being, this should work!