I’m playing a rogue using Flurry, Shift, Shadow Cascade and Synchronised Strike, and it seems that rapid combinations of holding flurry, then using one of the other attacks in quick succession, can make you come out of the attack channeling flurry. locking you into place and draining mana as usual, but no buttons are pressed. The lock ends when I press the flurry button again (right click in my case).
Can’t seem to reproduce it on command, but it’s definitely occuring like 4 times per hour of playing.
Flurry has Boundless Blows, ShockWave and Stolen Endurance