Teleport to new scene no more working after Unity and steamvr plugin update

The setup is very simple actually.

We have a few scenes set up with steamvr and vrtk plugins installed.
Every scene has player, teleporting and teleporting points in it.
We toggle the scene switch via teleporting point and added the scenemanager call to the teleporting point script, as suggested in some older tutorials (see below).

using UnityEngine.SceneManagement;

public void TeleportToScene()
{
if ( !string.IsNullOrEmpty( switchToScene ) )
{
Debug.Log( "TeleportPoint: Hook up your level loading logic to switch to new scene: " + switchToScene );
SceneManager.LoadScene(switchToScene);
}
else
{
Debug.LogError( "TeleportPoint: Invalid scene name to switch to: " + switchToScene );
}
}

That worked like a charm. Then we switched from last years Unity version to the actual one and the steamvr plugin updated too to version 2.

Instead of a clean scene switch we now have the old scene still running overlayed with the target scene.
Inputs are no longer working and there is a kind of mirrored view of the controllers visible.
It seems like the old scene was not closed but kept alive while the new one is loaded and running at the same time. All obejects (like player, teleporting point, area,....) have been updated and even removed and added again to insure they are all updated.

I hope that explanation makes sense cause its hard to describe.

Any help is apprechiated cause we need to get this running again soon.