With the patch that was pushed for bug 1616980, certain item statuses can no longer be set (or unset) via the copy editor (instead, they are to be set via other circulation actions such as doing a checkout).
However, there is a UX wart with the approach taken: If the copy is already in a magical status, the copy editor still presents a drop-down that ostensibly allows a different status to be chose. However, such a status change (e.g., from "Checked Out" to "Available" is simply ignored when saving the copy. It would be better if either the drop-down disabled all choices except for the magical status that the copy currently has, or if there was no drop-down at all and simply a display of the current status.
Evergreen 2.12
We often use that drop-down, so we'd much prefer the drop-down- with-only- some-choices- enabled approach.