Thank you for adding a post here on the Community page, @rwebb.
At this time, the data entered under the Description and Amount column will be removed when updating the products/services on your sales transactions. The ability of not losing the data on those fields is currently unavailable.
I know the importance of this feature when recording your transactions. I'll take note of this and pass along the information to our product developers. This way, they'll be able to know and work on in the coming updates.
Drop a post if you have any other questions. I'll be right here to help. Have a great day!