There are several reasons why your COGS account is incorrect. Let me share them with you so you can get this resolved.
The report date and report basis.
Selling of inventory items that you don't have.
To begin with, you'll want to check your report date and report basis to include the missing cost of your inventory items. Then, check the report details if there are inventory adjustments that can cause an incorrect amount of your COGS account. To do that, just double-click the COGS amount of your report.