Changing Milestone of Issue Marks "ToDo" Item as Done

I created an Issue in one of my Gitlab projects with a particular milestone. After creating it, the issue showed up in my Todos list. When I edited the issue to switch it to a different milestone, the Issue was moved to Done in my Todos list. This is not what I expected but perhaps it’s intended behavior. I’m running GitLab Enterprise Edition 9.0.4-ee 349b042 so perhaps this has been solved (a quick search in GitLab Issues didn’t find anything but perhaps I lack the correct search terms or methodology).

UPDATE: We recently upgraded to 9.2.5-ee 915a0aa. The problem also exists in this version.