Grand totals and subtotals within Tableau keep the aggregation that is applied to the measure. Therefore, in this example the grand total of the sum of Inv Amt is being divided by itself, thus giving the value of 1, which is then being multiplied by the overall average of Bucket Avg Days. The best way around this is to place the desired values on one sheet and the correct grand total on a separate sheet and place them on a dashboard together. To get the desired grand total, do the following:
1. Create a duplicate copy of Bucket (right click on it in the data box and select Duplicate). Place this on the level of detail shelf.
2. Create a calculated field similar to the following:
IF FIRST()==0 THEN
3. Place the above calculation on the view. Right click on it and select Compute Using-->Bucket (copy)
Hope this helps!
Thank you Tracy! Worked perfectly.
And thank you for the explanation as to why this was occurring.