Twice now, while returning to the lava tube beside the Castaway Circus Waypoint, I have landed on a patch of air, taken damage from the fall, and activated the Arcane Abatement trait mid-air before falling again moments later. For full information, I was using my character Wyrd Leverde, a Sylvari elementalist, carrying ember apples to feed Hal. Each time this happened, I dropped from the top leyline as I was approaching the very end, before experiencing the aforementioned invisible platform.