As written on the Kickstarter, Multiplayer for this game require a lot of rework, which was in part already ongoing for other reasons, now taking the first look at the game and running it with a Server-Client relationship, the first thing to address is that the Client can't replicate movements to the server,  the first culprit in this, would probably be the way the character is currently spawned in the level,  so the player controller isn't actually passing through.

So at the time of writing this log, the  Multiplayer is now being addressed from the basics aka Player Movement testing a Server-Client and a Client-Client relationship, once all this behavior is remade from scratch, it should be working.

I will disclose more updates once this is done, remember to help by backing the Kickstarter, it means a lot!