Because you have a calculated field in the filter, any other table calculation like window_max(Rank) will
give you not only the max rank of the view but the max rank of the whole dataset. So it is hard to get that single value.
The following solution is not elegant but it should work if you have a fixed dashboard size.
-duplicated sheet 1 on sheet 4
-create the following calc
if [%Running Total] < [Top x percent sales] then index() end
-put the calc on the Detail and add to Title.
It will show 1 to X in the title.
-Bring sheet 4 on the Dashboard and size it to show only the title, next add a mask in order to show only the X value.
You may have problems if you have a dashboard with automatic sizing, it may be hard to keep the 1 to always hidden, but with a fixed dashboard it should do the job.
Top x products ed mc.twbx 7.2 MB