Spells: bards unable to cancel song casting

[Elendae]

This has just started to be an issue since the last patch on Sunday night. It seems to be across the board for every song.

1) click a spell gem and begin casting.
2) try to cancel the casting by clicking a new spell gem.
3) casting bar disappears, but casting has not stopped. unable to cast another song until the last has finished even though it was meant to be cancelled.

most everything else is running smooth that I have tested since the patch last night.