Thanks for the step by step explanation, david. I can reproduce it on 3.5.3-beta1 now.
Here's the steps again:
1. Start a first instance of the game - this will be referred to as "instance 1" later -, go to the LAN menu and click the button to host a server.
2. Using the map filter, setup a game with 6 players. The first player is you (Contral = "Human"), all other slots have "Control" set to "Network".
3. Start a second instance of the game - this will be referred to as "instance 2" later -, go to the LAN menu, click on "Find LAN games" to automatically connect to the server.
4. On instance 2, switch to the slot of "Player 4" (the fifth slot, of white color).
5. On instance 1, reduce the map filter value to "4". As expected, the player of instance 2 is now listed as "Player lacks open slot".
6. On instance 2, you are still able to switch to the slot of "Player 5" (the sixth slot, of cyan color - though this color is not visible, only the button to switch the slot is visible). Switch to "Player 5".
7. On instance 2, the only information provided on your player now is "Not ready", no further information is provided on this player (the rest of the line is empty). While buttons to switch to other player slots are displayed, clicking them has no effect - you cannot switch to other slots anymore.
8. On instance 1, the only option provided on the instance 2 player now is "Block Player", no further information is provided on this player (the rest of the line is empty).
