Currently you cannot send a notification when a status is changed from a status X to something else
But it is possible to do indirectly, by using two issue rules and a hidden field:
Create a custom field of type Boolean (Yes/No), which is added to the issue field configuration that is used by the relevant project.
Create the field in ( General > Settings > Issue configurations > Custom fields) and call it for example "statusXset", and add it to the issue field configuration( General > Settings > Issue configurations > Issue fields, and choose the configuration that is used in the project)
The issue rules are created in (General > Settings > Issue configurations > Issue rules):
Rule criteria: Status 'Equal' (Specific status X)
Rule action: "statusXset" = Yes.
This sets the field "statusXset" when the status X is set.
Rule criteria: "statusXset" 'Equal' Yes
Status 'Not equal' (Specific status X)
Rule action: "statusXset" = Nej
Notification: Selected: (Here you set the users or user groups that should get the notification)
This rule sends a notification when the status is set to something other than X, and resets the "statusXset".
Remember to hide the field "statusXset" in the issue field configuration by set the access on the field to "No access" for all user groups.