Is it possible for you to attach a sample packaged workbook for us to look at?
Are you summing the calculation? If so it could be a level of aggregation issue that could be solved by altering where the sum happens.
If it is summed in your view this is what is happening: SUM(ABS(INT([Fiscal Start])-(INT([Include Month])+17))/ABS(INT([Fiscal Start])-INT([Fiscal End])))
Perhaps you actually need it to do this:
SUM(ABS(INT([Fiscal Start])-(INT([Include Month])+17)))/SUM(ABS(INT([Fiscal Start])-INT([Fiscal End])))
You may even need the sum to happen deeper in the calculation.
Out of interest is 17% the expected result? Is wrapping the date in INT giving you what you expect?
So, I'm not sure what was going on with the dashboard itself, but was in the process of generating a dummy .twbx file to attach to this thread when I noticed that the script I posted above actually was working as intended. And yes, 17% was the desired result. There was something in the dashboard that I was working with that was preventing a correct % and still don't know what the issue is.
This particular dashboard is blending 7 or 8 different data sources, so as a workaround I added the script as a calculated field in a different data source and brought it in to the dashboard by refreshing the data extract within the file. That seems to work. To be honest, I really don't see a difference in processing as the query times have not changed at all .