Bastian Gallenheart's mission appears to have an invalid destination.
Today the destination was a Sealed Hive deep inside of Nebezzdos.
I couldn't begin to list all the places I searched, but you can trust that I was very thorough in the Sunken Enclave, and even made my way out to Hyrelican's Seat.
It's there. Why it didn't fire beats me, unless you didn't find the spot. Changed it even so.