moon beams occasionally does nothing

I've experienced this a handful of times, I'll cast moon beams and target the area I'm trying to mesmerize does nothing...the target just disappears and the moon beams glyph isn't on the recast timer. So it lets me cast the spell again and it seems to work the 2nd time.

I've also seen where a moon beams glyph expires from the deck as you're targeting the spell and the target disappears, this is a separate behavior.