I have the exact same problem regarding not being able to update from Artist to Pro. Tried with the 28 digit-code and no ticking in the box "purchased" but it still wouldn't work. When I introduce the code in mypresonus profile to update the artist version, it lags and won't do anything further. Doesn't give a negative nor a positive reply. When I try it in the software, I get a message saying "You need to supply the product key for the product you want" or "Provided product can't be upgraded with that key". The solutions provided in this forum don't seem to be working either. Help.