bug
wait, are you saying it breaks your stealth when YOU put a dot on someone?
if so, that is working as intended.
if not, then bug.
When i cast a dot on enemy, it should break like with any ability use, yes.
It also breaks from me having an active dot on an enemy. So if i have a Twisting path on and enemy is standing there, the Shadow disguise breaks on every tick of that dot.
Sounds to me its that very very ancient bug thats not been fixed.
What you are describing is not a bug but an intended mechanic of cloak. Any instance of dealing damage (such as a DoT tick) will pull you out of cloak.