Shuttle skipped a new product, order or review because there is no quota left for it. On the free plan and the free trial, the quota is a monthly allowance of product transfers, order transfers and reviews stored from Etsy. Paid plans have no quota. On the free plan and the free trial, updates to products and orders you already transferred are never counted, so they keep running.
Why it happens
Your free plan or free trial allowance is used up. When this month's allowance for one item runs out, Shuttle skips new items of that kind until the allowance resets on the 1st of the month. To check, hover over the plan label at the top of Shuttle (it says "Free plan" or "Free trial") and read Included usage.
Your free trial or your subscription has ended. When a free trial or a paid subscription ends and no plan is active, Shuttle stops new transfers and updates until you subscribe. You can tell because Shuttle's menu shows only Subscribe.
How to fix it
If you are on the free plan or the free trial:
Hover over the plan label at the top of Shuttle to see which allowance is used up.
Wait until the 1st of the month, then run the transfer again.
To keep going now, click the plan label itself. It opens the Compare plans page, where you can subscribe to a plan. Subscribing removes the limits right away.
On the free plan, if you have not used your free trial yet, you can hover over the plan label and choose Start free trial instead. It raises the limits while it runs.
If your free trial or subscription has ended:
Choose Subscribe in Shuttle's menu.
Pick a plan and approve the subscription.
Run the transfer again.
See Shuttle's Available Plans for what each plan includes.
Still seeing it?
Contact support if your subscription is active, or your allowance still has room, and new transfers are still skipped with this message.