Bug or feature ?
Construction lines, and leaders don’t show up in scenes set to "Color By Tag, unless “Untagged” is set to a color. I guess they should also be visible with tag color “Untagged” not set, so by default material.
Setting a plan view to “Color by Tag” is very useful to me, I can view it as a colouring scheme for things “symbol color”, so that ie. the stairs is white in plan view no matter the color it has in perspective illustrations. But I would rather that any untagged objects don’t need a dark face color in order for guides and leaders to be visible.
After all, its not like untagged geometry will not show up in scenes set to color by tag if Tag color is set to default, so this seems a bit inconsistent.