Amazon have identified and fixed the issue with Amazon Shipping labels on their end. Our temporary fix has been removed and labels can be produced as before.
Shipping ServicePartial Outage - Linnworks.net
As a follow up to the issues with printing Amazon Shipping labels - we have released a temporary fix that will postpone the 'collection time request' by 5 minutes, which will allow labels to be printed successfully. This fix will be rolled back as soon as Amazon will resolve the issue with calculating the closest collection time on their end.
Shipping ServiceTemporary issue with Amazon labels
We are aware of an ongoing issue affecting Amazon Shipping and our team has been working closely with Amazon to identify the root cause of this issue to implement a solution as soon as possible.
The error message states "Error: InvalidInput: Invalid input Ship date cannot be in the past".