Hi jsharpe,

Thank you for joining the conversation. I'll share the information why the average cost is not calculated properly when building an assembly and guide you to fix it.

The Average Cost of an assembly item is calculated based on the cost of inventory parts. Therefore, you need to make sure that the individual parts have their own costs. Otherwise, you won't get an average cost, like in the screenshot below. 

After knowing which item it is, edit it, and add the cost. Then, go back to the assembly item and deselect and reselect that item.

On the other hand, if you want to find references for QBDT, just click the Topics menu above and select a topic.

Please let me know if you have questions as you do some edits. I'm just around to help.