I've noticed a strange bug when using guides.
Please see the attached .afdesign file.
I dragged from the top ruler to create a horizontal guide on the page. I then used the 'create artboard' button which replaced my page with an identically sized artboard. I then duplicated that artboard.
I decided I no longer wanted the horizontal guide, so I dragged it back up the the ruler to remove from the page.
When I go to View > Guides Manager it shows no guides on the page. Same thing if I select each artboard and check the Guides Manager.
However, if I click and drag a selection square anywhere on an empty part of the page, my removed guide shows up on the screen! (see screenshot).
list-tick.afdesign