Closed iterations in filter
There is a recent change in GitLab which probably caused, that closed iterations are not shown in the "Iteration" filter in issue boards, issues page. This is probably something new, as I was able to filter out issues assigned to closed iterations few weeks ago.
Can You confirm, that this change is intended and it is not a bug? It is useful to have the possibility to select closed iterations in filter sometimes.
There could be a context sensitive Iteration filter implemented. When I search closed issues (I switched to "Closed" or "All" tab in the Issues page) then the filters could allow to search for closed iterations. When I search open issues (I am in the "Open" tab in the Issue screen), then the filter allow to search for open or for upcoming iterations.