What may help you is trying to understand the three things that influence your workflow:
Viewpoint>View>Drawing.
And that is the order in which they are created. In a typical workflow for details, the viewpoint (the independent detail), the view (in your view map), and the drawing (on the layout) will all have the same name. Working backwards, the drawing gets the name automatically from the view and the view gets the name automatically from the viewpoint.
In your case they are different: You have renamed the drawing and although you didn't specify it in your post you have possibly named the view to something different than the name of the independent detail.
Your drawing settings show the source view (that is the view in your view map, not the viewpoint in your project map) is an internal view located at Proposed Dwelling/Details/B1 Engineer Beam Details 1:10.
The screenshot of the view map does not show the entire Details folder, and the view could possibly be further down in the list. The best bet is to right click on the drawing and select Open Source View, that will open the source view of that drawing in your view map. If it doesn't then the view has been deleted, through your Navigator/Organizer.
BUT it doesn't
necessarily
mean that the viewpoint has been deleted. You could start manually opening all detail viewpoints and looking for your content. Then you could just make a new view and re-link the drawing to it.
I would start with B1 1:10 Detail.
With that all said, you really are fighting the program using these methods. All of this should happen automatically, consistently and predictably. Then you can use more features, such as back referencing.
I hope you get to make your change soon, you won't believe the difference it will make to your productivity and happiness!
Good luck!
Cheers,
Link.