I tried that - it’s currently ticked. When I unticked it, it replicated the problem exactly. I had switched styles midway through drawing to hidden line so I could print a plan like version for a client. Could that be an attribute of the style? So I just switched styles to test the theory. However, I could still view the guide line. So that’s eliminated as a possible cause.
I must have accidentally un ticked it, but for the life of me I can’t think of any reason why I would open that pulldown menu.
Maybe I accidentally hit a keyboard shortcut that did that? I sometimes miss shift and hit ctrl. Or missed the backspace and hit one of the Fkeys. That’s the only thing I can think of that could have caused it.