Are you able to provide an example workbook and a screenshot of the expected result?
Look at this example:
Percent of Total is defined as:
So, inverse of Percent of Total can be calculated as
These are "Table calculations" and the TOTAL function adds all values in the partition (the numbers in the view). That leads to the odd Grand Total of 100% for the Inverse Percent of Total because TOTAL(SUM([Measure])) = SUM(Measure) at the bottom line.
Hope this helps