The issue with the Quantity fields is probably for auctions only. Here's the scenario where I see it, and I was just able to reproduce it.
-Select multiple auctions and click Basic Edit
-All quantity fields will be populated with '1' and are non-editable
-Remove any auction from the list by clicking the x on the right side
-All quantity fields are now blank, and still non-editable
-You are unable to save and unable to fix the error, so the only option is to close the window and start over