Can anyone help as to why I'm getting Not Specified amounts in the sapes by product /service detail reports?

The amounts will show in this section if they don't have a Product/ Service assigned to them, oufnc-treasurer.

We can click on the transaction or amount to verify it. If you assign an item to them they'll no longer appear on the Not Specified section but to the product or service you assigned to them. 

You can check out this article that'll help you customise and display the report you need.

I'm just a post away if you have any other questions.