Adding to what others have said, Bard just has really bad sync with WM atm.

For example - Heavy Shot - Weave Bloodletter during CD - Another Bloodletter proc - Next Heavy Shot cast is cancelled due to a close weave. This goes for casting buffs - Buff right before casting a skill - interrupt. Also, idk if it's just me, but for some reason all my attacks get canceled when the boss starts to move, ie AS1, after split and if the tank moves the boss to the other side of the room, all my casts cancels until the boss stops moving. Weird.