Multiplayer signaling actions are asynchronous. If you put them in the same event as the layout change action, you will leave the layout before either of the signaling actions complete. Notice that the "Signaling: left room" and "Signaling disconnected" message logs never show up, even though there are events to log when they happen. So basically what is happening is that you never left the room as far as the signaling server is concerned, therefore the "join room" action will no longer work even if you leave the layout and come back with a new peerid/alias. The second time you go to the game layout, since you're already in a room and the auto join room action fails, the following "On Signaling Joined Room" event does not run and assign paddles to host/peer.
If you do the following, it works fine:
+ Keyboard: On Escape pressed
-> Multiplayer: Disconnect from room
-> System: Reset global variables to default
+ Multiplayer: On signalling left room
-> Functions: Call AddLog (message: "Signalling: left room")
-> Multiplayer: Disconnect from signalling server
+ Multiplayer: On signalling disconnected
-> Functions: Call AddLog (message: "Signalling disconnected")
-> System: Go to Login