@Derelict:
Harden Glue appears to correct this, but that's pretty anecdotal.
Never could reproduce this lolcal issue… I have harden-glue: yes enabled everywhere. So, sounds like a pretty good guess I'd say.
@cmb: Can we get harden-referral-path exposed in the GUI as well? (Probably not default on, but visible.) Also, harden-below-nxdomain.