The most recent PTS patch added an in-combat requirement to all ultimate gains (or it claims so, anyways).
This is the absolute stupidest nerf possible for sets like arkasis.
It was stupid when they did it to clever alchemist, and it's stupid now.
You will often drink a potion out of combat, and then the set is effectively on cooldown for 30 seconds-45 seconds for no reason whatsoever.
The better solution would be to either
a) add an equipment lockout debuff for 30 seconds (which would also solve the dilemma with other sets like master architect),
b)
remove the buff gained when an equipment piece is changed (this is how power surge works, you lose the buff if you unslot the skill after casting),
or
c)to put a player into combat for 5-10 seconds.