You might be missing EventSystem in the next scene or some other Ui Mouse control script? Try using all the files from the good scene or duplicate the scene, rename it, add it to the Build then set it as the destination scene using vLoadLevel Trigger.
Check the Inventory Events on the Player Controller, you should have stuff like LockCursor and ShowCursor, if all Events are empty a duplicate of the good scene will have them all filled in properly.
Don't Destroy on Load isn't the problem and I don't think Invector has that working properly anyway. I don't think anything Invector does survives scene changes, "always on" without a Do Not Destroy Save System "singleton"or Game Manager "singleton", I could be wrong, persistent data.