(Note: I created a very simple example recreating the problem)The elevation shown in front of the joinery, surrounded by an in-place family of walls.
So I started my usual process of elimination, starting with checking where the elevation line was, view extents, visibility graphics, filters, etc etc.
I finally noticed when selecting the in-place family (representative of the existing walls), the category assigned wasn't in-fact 'Walls'. It was 'Structural Columns'. Ah huh! So we updated the category to walls and there appeared our joinery in the view!The view with the in-place family category set to 'Walls'.
Just another thing to add to our list of things to check when troubleshooting. Worth noting this difference in behaviour between the categories too.