Hi, I have the same problem. Former purchases with some other price and discount can not longer download the premium file. Also some other creators had this issue, they could fixed it sameself. It has to do with the settings for prices and discounts. Maybe because of the price changes in the past, such problem can only be avoided in the future by a separate download option for the free version. Would be nice when you could take a look at it, thank you.
(The user "chroma-dave" had the same issue with one of his assets and could fix it. Maybe you can get in contact with him.)