I killed the Ancient Stone Beast while it was standing on one of the hidden doors in the Earth Temple. I killed it but didn't receive the "items falling to the ground" message. I assumed the orb would be on the square where the ASB was killed, but no luck. Upon searching the door and revealing the square, there was nothing there. I've dug out most of the earth temple, used wands of item detection, etc, but can't find it. When I quit the game, the orb didn't even appear on the generated artifacts list.

The guaranteed drop functionality changed recently, I know, but I'm pretty sure this is a bug. Or is there some other way I'm supposed to recover the orb...?

(this is release 49 win64)