I’m becoming a bit dubious about using kevlar beaded tyres tubeless as I’ve had a couple stretch massively on me.
Coincidentally, the last one to do so was a 2.1 Advantage. Went from being a tight fit on the rim to as loose as a Panaracer. It burped, I pumped it up to about 30 psi (with a hand pump) and BOOM!, covered myself and my friends in latex. It then rolled off the rim when I punctured the tube the next day. From comments above, I would guess that the bead wasn’t seated too well, which could have caused the problem, but I’d run the tyre for a couple of months with no issues.
Never had the problem with steel beaded Maxxis or Bontrager tubeless-ready. I’m now giving spesh 2bliss a whirl.