Rocketman Rob,
Welcome to the galley.
A little bit depends on where you're cooking because of the local humididdy ~ er, hewmaditty !
The dang HUMIDITY levels.
Here in the swamp in the summer it takes a lot more fuss but on a good dry day I find a good, sweet "finishing sauce" brazed on at about 215 to 225 degrees for an extra hour (or two) without foil does the trick.
Try a terriaki glaze sometime for a change.
Naturally, dry climate works better.
Or you could just tease the neighbor's dog.
No, no! I said tease not braise.
Bark is a build-up of caramelized sauce as stated above by. the more sugar in the sauce, the more caramelization.
It only occurs by intensionally making it happen. Repeated misting, swabbing, using a specifically made finishing sauce can all be used but the process still requires de-moisturing the taisty goo until it gets almost to the jerky stage.
That takes time and watchfulnessness. Low and Slow, Bro. Low and Slow.
And share photos when you get it. We all love to see other folks success.