I deleted two milestones that were assigned to ~10 issues. In the issues tab view, the issues still had the assigned milestone. When I click on one of the 10 issues, the milestone is empty (-------) and the deleted milestones are not listed. It appears that the milestone shown in the issue tab is not exactly the same as that in the issue view.

To recreate, I it should be sufficient to:

create an issue

create a milestone

edit the issue to attach a milestone

delete the milestone

look at the issues tab

look at the issue