Thanks for contacting support. Apologies for the issues you are having with the AppCast XML file.
The issue with the XML file seems to be one of the cache. The team has confirmed that it might take up to a week for the appcast3.xml file to update. That is by design and the team has been notified of this.
@foigus I noticed that v83 of Sketch is not available in the Appcast XML @ https://www.sketch.com/appcast3.xml so I contacted Support.
Here's their answer:
Can you change the XML URL in the recipe? Thanks!