Hi Microwave,
I just thought I'd let you know about my experiences with HBD. Basically they are pretty much the same as yours, I have also have feminised seeds and so far none of them have flowered without reducing the day length. Infact, the only one that I have managed to recover any bud off was flowered under 12:12 right the way through - usually I would only have an auto on 12:12 for a couple of weeks at most if it needed extra persuasion to flower. So far I've grown 4 and none have autoflowered, and I am seriously considering just binning the other 6 seeds as growing them has just been so much hassle compared to a true autoflower.
I assumed that it was old seed stock from an early generation of the strain (perhaps one that shouldn't really have been released as an autoflower for a few more years), and switched my retail seed supplier (I didn't get mine from Herbies, so the problem isn't just with them). It looks highly unlikely that I will try any of the Short Stuff strains again, as I had quite a few similar issues (although less serious) with a pack of MI5 I got at the same time.
Hope you manage to get some buds, it was a nice smoke when it eventually arrived.
Cheers,
The Doctor