Hi,
I've been looking and experimenting for hours and can't find a solution.
In a project I have setup for a team we have the following setup
Initiative
Epic
Story
Story
Story
Sub-task (Summary is product A)
Sub-task (Summary is product 
Sub-Task (Summary is product C)
Story
Epic
Story
Story
Story
Sub-task (Summary is product A)
Sub-task (Summary is product 
Sub-Task (Summary is product D)
Sub-task (Summary is product E)
Sub-task (Summary is product F)
Sub-Task (Summary is product G)
Story
This layout continues into 56 different Epics totally 622 sub tasks across the project.
This is fully intentional, as a requirement from the team. It has additional things like labels and components so I could show the relationship of the "product" across different Epics.
So what I'm trying to do now is replicate the reporting that they were doing in Excel (requirement was to move the team away from using Excel and into JIRA), part of this is to show how many UNIQUE sub-tasks there out of the 622 on a dashboard.
The creation of a dashboard isn't the problem, it's the JQL query to do something like "exclude duplicate summary" as the summary will be exactly the same.
It's worth noting I am on :-
JIRA Service Management Application v10.3.8
I work for a large company, don't have Admin access nor can I download/install any plugins.
Hopefully somebody can give some guidance on what seems simple but I'm rapidly losing my hair on it :-)
Thank you in advance.