That does sound like some sort of defect, possibly heat-related, but I will add my own observation that the amount of charge on the battery makes a difference. It won't regen if the battery is fully charged and it won't assist if the battery is low. One reason is apparently because AS doesn't function unless the battery has a lot of charge. So if you're really riding that accelerator and you've dropped the battery meter faster than it can recharge while you are driving, then maybe that's the problem. Without knowing how you drive, though, I still suspect a defect.