In setting, the accounts for export of positive and negative inventory adjustments the dropdown menu only gives me the option of COGS, Expenses and Income.

I would have thought these adjustments (at least positive adjustments) should code to the asset account for inventory. Am I missing something?

Negative and positive inventory adjustments are recorded as Expense or Income and not against inventory because you may do a manual inventory adjustment if stock gets lost for example.

If you access the Help file in QuickBooks and search for inventory adjustments, it will list the process that QuickBooks follows to make such adjustments . The accounts listed in the help file are the ones listed in AdvancePro drop down for making the inventory adjustments. The change in inventory numbers is recorded, but QuickBooks will also record the inventory change as a dollar amount because the stock costs a certain value and that must be reflected when the quantity changes.