In a project, people wish to delete a fix version from a set of issues (these issues have one or two other fix version values too). The issues are resolved and closed. It often proves impossible to delete this fix version: it reappears immediately after deleting it (from the View Issue screen). Also via (bulk) Edit, it doesn't work. There is no error message or so. Even if this is proper functionality, it seems not very user-friendly to have a value reappear immediately without any warning/error message.
What I did find: in some issues the fix version can actually be deleted. In others, fix version can be deleted when reopening the issue (i.e. resolution becomes empty, status becomes open). In others, it's not possible at all, even after reopening.
In the workflow, there is no status property defined such as 'jira.issue.editable', so this can't be the reason.
These issues are from an Agile project, used in the 'classic' way (so in fact these versions are sprint names).
Am I missing something? Is this a bug? What could be the reason?