I am not so sure, we do not have the time to dig too much into dota2. I believe some part of the Steam's Dota2 item API has changed. Or you have just accessed it while it's down. Can you access your dota2 inventory now? As the moment of this post it is working for me.
I accessed it when there was no red "DOTA" label. I still cant access "my steam" (dota) inventory in dispenser as of now, it still says "no inventory" and there is no red "DOTA" label.
