There was a post from Admin, about midway in this thread, explaining that there are actually *two* different accounts, one is the forum, the other is KD. To change your KD subscription they suggested that you find an old KD email, scroll down to the bottom, and click where it says "Manage Your Subscriptions". I just did that and discovered that I wasn't subscribed to anything. Don't know if that'll fix my problem, but hopefully it will.
Seems like they'd post something like that *prominently* in an FAQ or whatever, since the link to updating the KD subscription isn't readily apparent.
Honestly, this is the first time I've even been in these forums (who needs them, frankly, when we have Ravelry) and only came out of sheer frustration.
ETA: This has *fixed* my problem, as I have begun receiving emails today.