Shuttle skipped a stock update for this Etsy listing. The listing keeps one quantity for the whole product, and Shuttle is set to leave that quantity alone.
Why it happens
You see this message when both of these are true:
The Etsy listing has variations but only one quantity. On Etsy, the quantity is set once for the whole listing instead of separately for each variation. Open the listing on Etsy and check whether each variation has its own quantity.
Shuttle is set to skip these listings. The setting that updates a listing's single quantity from your Shopify variations is turned off.
When a Shopify variation's stock changes, Shopify has a quantity for each variation, but the Etsy listing has just one quantity to update. With the setting off, Shuttle leaves the Etsy quantity as it is.
How to fix it
To let Shuttle update these listings:
In Shuttle, go to Settings > Stock Syncer > Shopify → Etsy.
Find When Etsy manages stock on the product or option.
Under Quantity managed on the Etsy product, tick Update the Etsy product quantity from Shopify variations.
Click Save.
Shuttle then sets the Etsy listing's quantity to the lowest quantity it finds across the matching Shopify variations.
If you want each variation to have its own stock, change the listing on Etsy so each variation has its own quantity. Shuttle will then update each variation separately.
For more on how Etsy listings can track stock, see Handling Etsy Stock Management by Product or Option Level.
Still seeing it?
If the setting is on and saved and this message still appears on new stock updates, contact support. Tell us the product name so we can check the listing.