I would guess all those B7XX type ratings may scare off some people, fearful that if they get you aboard, you'll run off to the airlines when the "Great Pilot Shortage" really hits.

Not sure what to offer you other than to stay persistent, and try to meet folks face-to-face so you at least have an opportunity to convince them that you really do want a corporate flying job. Sounds like you've made some calls already. Maybe make them again just to keep your name fresh in everyone's mind, or go out in person.

Sorry, wish I had a silver bullet for you.