The gold does not always come even with 3 stacks still there. An example would be Diana's Crescent Strike. There are also some characters that can use basic attacks but it doesn't work on the towers most of the time. This happened when I was using Nidalee.
I have a similar issue with the item, I just finished a bot game and started with spell thief's edge. when i came back to the fountain much later, I directly upgraded to frost queen's claim, but the tribute triggers stayed as spellthief's edge. I was only getting 5 gold per hit, and only if i had not killed a minion in the last 30ish seconds.
