... even tho the patch notes say they shouldn't be interruptible. Pls fix - or even better - just remove the cast time again.
from the patch notes:
Adjusted the animations and cast times for many Ultimates that are meant to have high impact to better synchronize their attacks to their animations. These abilities cannot be interrupted, and canceling them or being stopped while casting them will not consume your Ultimate.
So the channel can be stopped, either interrupted bij enemy or canceld bij player. After succesful channel the ability can't be interrupted anymore
Adjusted the animations and cast times for many Ultimates that are meant to have high impact to better synchronize their attacks to their animations. These abilities cannot be interrupted, and canceling them or being stopped while casting them will not consume your Ultimate.
and:
Canceling the Ultimate will not consume resources, and this cannot be bashed/interrupted from abilities.
They are stating that in the general part too: "These abilities cannot be interrupted". And dawnbreaker is no exception, it is interruptible like all other ults with a cast time.