1. Select Multiplayer -> "Host new session" -> LAN
2. Select attached mission called "$_onPlayerConnected_bug.VR"
3. Start another instance of the game and connect to your LAN game.
4. Select a slot and wait until you can move.
5. Switch back to the host.
It will report the connected clients ID in the chat.
6. As host, press ESC -> "Save and quit"
7. In the mission select screen, RESUME (not "restart"!) the same mission
8. As client disconnect and reconnect from the LAN game. Select a slot and wait until you can move.
9. Switch back to the host again.
This time nothing will be reported. This can be fixed by adding another (dummy) event via BIS_fnc_addStackedEventHandler. E.g.:
["dummy_OPC", "onPlayerConnected", {}] call BIS_fnc_addStackedEventHandler;
Finally, repeat the same thing with the other attached mission called "$_onPlayerConnected_bug_fixed"
This time it will report the connected clients ID, because a missionEventHandler "loaded" will add another "onPlayerConnected" event which will resolve the serialization issues.