in the assembly item screen, the cost block per item listed comes from the cost block on the item screen – so check the cost block on those items that show zero in the BOM listing

However, that cost shown is a best guess kind of thing for reference only.  Cost […]

Resolution for 'BOM cost issue: 'Average cost of inventory part is blank while there is average cost, thus BOM cost is not accurate because cost of those items is zero' available: Yes.

The BOM cost issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the BOM cost issue yourself by looking for a resolution described in the article. If it is a complex BOM cost issue or you are unable to solve the issue, you may contact us by clicking here or by using other BOM cost support options.

For more information about resolving issues related to BOM cost in Quickbooks/QBO or to get support for the issue 'Average cost of inventory part is blank while there is average cost, thus BOM cost is not accurate because cost of those items is zero', click the link below: