% of total in report column showing value when data is zero

% of total in report column showing value when data is zero

I have a report in which I am showing a whole lot of specific activity across a large number of items, and I want to show the % of the total for each item based on the total activity for that item as a share of the total for all items.

Sometimes this seems to work, but in many cases the specific % is irregular. For instance, if there is no activity value in a particular item (0). It lists this item as .39% of the total. Other times, there is wide disparities in the amount and the % value. For example, one item has 74000 units and is 4.3% of total, whereas another is 3875 units and displays as 3.1%. I've pasted a picture of the table below for reference.

Anyone have an idea what is going on?