When your products do not have the corresponding quantities in the inventory or have negative values in the stock field or available. It is necessary to make an inventory adjustment.
Database > Products > Inventory Adjustments
Plus + (new)
Quantity > finish
if you want to check the adjustment, you may do so at Products > View Edit > Inventory Adjustments > Report
You may update the inventory from a CSV format file, too. Products > View Edit > Inventory Adjustments > Cloud (to update CSV file)
Products > View Edit > Inventory Adjustments > Download CSV file, update & upload
The adjustment done on itmes can be review at Products > View Edit > Click ? Inventory History
