Dragon tooth bug
Unfortunately, with skills with cast times, if you get interrupted in any way, even a micro-second before the cast time ends, the entire skill does nothing. The same thing happens with Eruption, Ice Spike, and other similar skills. It’ll also happen if you dodge or sometimes if you queue another skill too soon after the first.
No idea if it’s intended, but the result of interrupt or dodging seems like a legit consequence for being interrupted.
Queuing a second skill should not interrupt the one you’re currently casting. I think this may be a result of some of the cast and aftercast times ANet has tweaked.