I can add labels to a Jira ticket with Python but cannot remove one. For example:
ticket.label_list = [lbl for lbl in ticket.label_list if lbl != 'OLD_TAG']
ticket.commit_changes()
I have worked with similar manipulations in Jira using Python. In my experience, directly modifying the label list of a ticket and then invoking commit is usually effective when done with the correct API client. One thing to consider is that some Jira instances are strict about partial updates, so the removal of a label might require re-fetching the ticket to confirm that the operation was applied. Additionally, ensure that any caching mechanisms in use on the server side are cleared to reflect the updated label immediately. Double-check the API version to maintain consistency in behavior.