https://classic.wowhead.com/quest=466/search-for-incendicite is missing the pre-quest https://classic.wowhead.com/quest=467/stonegears-search . It is not available before that, despite showing on the map.

It is available if you abandon the breadcrumb quest. Tested this myself. Stonegear's Search is not required for Search for Incendicite.

Closing this as it is working as expected.