I lost about 65,000 experience and five levels from crafting (-45,163 xp from making six saffron, -18,672 xp from making six awesome stews, and -2,626 xp from making another six saffron). In all cases I've received the "You have received all possible XP from making these today" message.
The experience has been promptly restored by a helpful staffer, but since the ticket has been marked as resolved and this issue is not in the known bug list, I'd thought it would be better to mention this here as well, lest the report of the underlying error gets lost in the system.
I haven't tried crafting again, and I'm still a bit nervous about trying, to be honest. :)