Buddy can't join on almost all of the workshop multiplayer campaigns

[Frogt]

Every time he wants to join my MP lobby, he gets a black screen in almost all of the workshop campaigns. Even the ones that I've made myself.

We got a couple of them to work (mostly the T55 missions that come with the DLC itself)

Anyone knows what can cause this? The black screen happens when presses join (i.e of the locker room there's a black screen)

Also If he tries to start up a server he can't even select these campaigns.
Once he selects one of them it immediately switches back to the default MP campaign (freeflight/flyshow)

He doesnt own any of the DLC, but I dont think that should crash the game right?
He re-installed multiple times and verified the files but nothing seems to work.

[醉仙望月]

Please provide his Player log from when the issue occurred.
C:\Users\...\AppData\LocalLow\Boundless Dynamics, LLC\VTOLVR\Player.log

[Frogt]

I think this is when the issue occured:

 VTMPMainMenu: Successfully retrieved the MP scenario!
Fading out
Lobby message from Frogt: load_0.7023184
Unpausing Controller Events
Uploading Crash Report
NullReferenceException: Object reference not set to an instance of an object
  at VTOLVR.Multiplayer.VTMPMainMenu.LaunchMPGameForScenario (VTScenarioInfo s) [0x00000] in <0de4834e7edd4401b198638f3c87b4df>:0 
  at VTOLVR.Multiplayer.VTMPMainMenu+<ClientLaunchLobbyMissionRoutine>d__49.MoveNext () [0x00320] in <0de4834e7edd4401b198638f3c87b4df>:0 
  at UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) [0x00026] in <72b60a3dd8cd4f12a155b761a1af9144>:0 

Lobby message from Frogt: load_0.8023896
Lobby message from Frogt: load_1
Lobby message from Frogt: $sys_hostCreated
Lobby message from Frogt: load_1
Lobby message from Frogt: $log_Frogt has connected.
[XR] [OpenVR] XR OpenVR Display Stop
[XR] [OpenVR] XR OpenVR Display Shutdown
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
[XR] [OpenVR] Shutdown
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
XRTextureManager::RequestDestroyTexture
[XR] [OpenVR] Device disconnected (stopping provider). Handle: -2140676400. DeviceID: 0
[XR] [OpenVR] Device disconnected (stopping provider). Handle: -2140676400. DeviceID: 1
[XR] [OpenVR] Device disconnected (stopping provider). Handle: -2140676400. DeviceID: 2
[XRInputSubsystem] A device disconnection with the id 0 has been reported but no device with that id was connected.
[XRInputSubsystem] A device disconnection with the id 1 has been reported but no device with that id was connected.
[XRInputSubsystem] A device disconnection with the id 2 has been reported but no device with that id was connected.
VTNetworkManager OnDestroy
XRLoaderSelector.StopXR()
 - Stopping Open VR Loader
 - Error: It may have already been stopped.
LeaveLobby()
Uploading Crash Report
NullReferenceException: Object reference not set to an instance of an object
  at Steamworks.Data.Lobby.Leave () [0x0000b] in <22a621e05a62440fbb51b91caeebc61d>:0 
  at VTOLVR.Multiplayer.VTOLMPLobbyManager.LeaveLobby (System.Boolean checkMPScene) [0x0005b] in <0de4834e7edd4401b198638f3c87b4df>:0 
  at VTOLVR.Multiplayer.VTOLMPLobbyManager.OnDestroy () [0x00000] in <0de4834e7edd4401b198638f3c87b4df>:0 

Invoking OnVRHeadChanged
VRHead is gone! Activating fallback camera.
SteamClient Shutdown