Units Assigned * Usage- Cost Roll Up Issue

Hello Team,

We have a scenario wherein there are 14 units of a specific resource that are involved in the manufacturing process of a SKU. While setting up the Work definition

1. We associated a resource and in the usage column provided time taken by one unit resource to manufacturing one unit of the FG.

2. In the Units Assigned column provided total number of units of involved.

We expect system to consider Units Assigned*Usage value while calculating the Rollup costs. However it does not do so. Can you please let us know, what could be the reason it doesn't?

I have attached the screenshot of resource configuration when associated to a work definition.