In a sleep-deprived state, I logged onto my druid (gathering alt), chose some i649 legs from the Great Vault’s delves track, enchanted them, then decided to go to the catalyst and spend one charge to upgrade to my 2pc set bonus (tier chest from last week’s Great Vault). As I clicked, I thought, oh no, this is going to blow away the enchant, AND the Leech upgrade they came with. At first I thought they had disappeared altogether (UI bug that made the icon disappear), but when I closed and reopened the character screen there they were, now a tier piece, still with the enchant and STILL with the Leech bonus.
Is that working as intended? I thought that in patches past catalyzing gear into tier removes enchancements and bonuses.
Edit: looking less like a bug, as I just got a different piece of tier gear on a different character through the Great Vault, with Leech built in.