As of the new Factorio patch 2.0.23 this issue has been resolved.

I don't need technical help. I found a workaround so we are able to play. Simply reporting that things worked perfectly last week and now suddenly after a patch things have been behaving strangely/not working. We were able to reproduce this issue across multiple reboots during the course of a few ...

1. What did you do?
Tried joining Steam friend's multiplayer game through the "Join game" button in Steam friends list while Factorio was already launched.

2. What happened?
Literally nothing. No popup, no error, nothing happened.

3. What did you expect to happen instead? It might be obvious to ...