There's another field you have to use if you want 'up to the minute' inventory totals, and that's the Quantity Shipped not Costed field. Add this to your formula.

If the day end in OE is done, this will update all of the necessary fields for the IC item quantities. Quik Reports can only read the data values for the quantity fields, and if transactions are entered and don't immediately update IC, then Quik Reports can't report on it.

This would be the reason for values in IC standard reports differing with Quik Reports.