Since version 7.2.0 you can see the 'Time in Status' of an issue.
where you can see:
by Status: how long the issue has been in each state.
by Transition: how long the issue has been in the state of origin of the transition.
by Assignee: how long has each user been assigned in each state.
How can I see 'Time in Status' of an issue?
Just “click” on the status in any of the application's functionalities (Hierarchy, Dependency Table, Matrix...)