Price at Product Category level does not work the same as Price at All Items level

Summary

Price at Product Category level does not work the same as Price at All Items level

Content

1. Defined an Item and associated to a catalog and a category
2. The catalog has been assigned to Pricing Parameter "Product Catalogs" so that the prices can be defined at the Product Category level in the price list.
3. Defined the Price for the item under Items tab with effective dates of Jun 1 to Jun 8 for $2.00 and Jun 9 to Jun 22 for $2.10. 
4. Also defined a price under Product Category tab for the item's UoM with start effective date of Jun 1 and no end effective date for $0.00