I'm curious, what was it before then? I thought they always decayed into Standard Goods? The Wiki page (that was last edited in August of last year) says the same:
The Ascended Goods are subject to a special decay. You can store unlimited amounts of Ascended Goods in your Main Hall, but they will decay overnight by 10%. Ascended Goods decay like Mana, Divine Seeds and Unurium but, unlike them, they will not just disappear but "transform back" into the original resource. For example, if you have 1000 Primordial Minerals, and the decay is 10%, you will lose 100 Primordial Minerals overnight and gain 100 Marble.
That just might be the official public line for the bug fix. However, there are a couple major exploits possible with Ascended goods, that I, and no doubt others too, have reported to Inno (in my case months ago now). Maybe the update actually fixed these.