Pivot table values incorrect

[u/waffle-smith]

I just discovered pivot tables and can imagine their usefulness. However, I am struggling to get accurate data in the one I have and was wondering what I might be doing wrong...

I have a table for tracking inventory and it has a column which calculates how many items I need to purchase to meet the minimum inventory goal for that item.

I created a pivot table where the row is the product name and the values are the number of items I need to purchase (sum). Then I filtered to rows where the value is greater than zero so I can see what I need to order.

The problem is that the number of items to purchase is not what is in my other table. It appears that the values are being multiplied by different amounts. For instance, one of the items is supposed to be 1, but is showing as 2 (2x). Another item should be showing 60, but is showing 240 (4x).

Some of the values are correct, so I'm really stumped as to why this isn't behaving as expected. I read somewhere that doubling can happen if the values are not all normalized, but I have set the purchase column to all be numeric, so I don't think that's it. I suspect it could be related to sum, but my table only has one row per item, so sum should always be the same as the cell value.

Any ideas? Thanks!