It happens rarely with this boss, but it usually happens if you use bomb rocks on the Scornets. Also, about 20% of the time, when battling Vehemoth Phosbat in story mode, the music will cut off after you light up the big bulb and start the real fight. I also didn't experience it until version 2.0.0. It seems like I'm the only one who's had these glitches happen. Weird...