Hello
I dont understand the auto buy function with tax on a card. Usually I use the autobuy function to be quick and simple, so that if I click on a card that has additional debt on it, I want to play all treasures and got the debt paid back immediately. *IF I DONT* want that to happen, I can play the money one by one, but it is the other way around, which often results in undos.
The autobuy function will at the moment only generate the minimal amount of coins and potions to be able to legally buy the selected card.
For a card with an intrinsic debt cost (like Engineer, which costs 4 debt), that minimal amount is 0 coins and 0 potions. So even if you have 2 Silvers in hand, autobuy will *not* play them in that case, and you will end your turn with a bought Engineer, 2 Silvers discarded uselessly from your hand and 4 debt.
If debt tokens are on a pile due to Tax, then ,as you experienced, it will also not be taken into account buy autobuy. I mentioned that problem previously (http://forum.shuffleit.nl/index.php?topic=1785) and the developer agreed that the debt part would be a good idea, but it hasn't been implemented yet.