That field shows either the current error count for the selected listings, or there are no errors the listing fees as computed by eBay. However, there’s a know bug where this field does not update the error count as you fix them in the selected listing.
When GarageSale is hanging, can you recored a “spin dump”. This post contains instructions on how get one:
Could you post a screenshot from GarageSale 6 that shows the feature you are talking about?
Is this happening for listings created via the “New Listing command”? Or listings you imported from GarageSale 6?