Quantity must be consistent across all products - Error

This error can appear when new variations were manually added to a listing directly on Etsy, and quantity variation was not enabled. Follow the steps below to update the product:

1. In your Etsy account, go to Shop Manager → Listings → Edit listing.
2. Scroll down to the Variations section.
3. Next to the variation, click the gear icon or "Edit variation options". Inside that, make sure that the “Quantities vary” option checkbox is enabled.
4. Once it’s enabled, a table should appear letting you enter individual quantities beside each weight option (6 kg, 8 kg, etc.). Save/upload the changes.

Repeat the steps for all Etsy variations that do not have this option enabled. Try running the "Update Price & QTY" action from the Selling List to verify the results.