Spectral Spellbinders are not respawning when killed

Stingard

The Spectral Spellbinders in New Haven are not respawning when killed on Chesapeake.

Khyro

The New Haven area is like a mini-champion spawn (with Drelgor being the boss). Try killing the other mobs in the area to progress it. Spellbinders come in wave 2, so there may have been some leftover spellbinders from a previous cycle and they aren't respawning because the spawn needs to be advanced.