I was running a dungeon with Squall tearing things apart with the BSB2.
I had two draws and my roar hit darn hard with 6 heavy hits.
But since he is Legend dived and using the chance to double cast spellblade materia he decided to do a second roar strike.
However the second hit was only 4 anemic hits and when I looked at Squall he no longer had the draw orbs and he was not in burst mode for his next turn.

Best I can guess is that if you run out of burst mode but you get one more action with it it clears the burst buffs before double tapping.
Not sure if the same effect works on Ex modes or chases.
I don't know if the timer moves a little, as I have seen in magicite dungeons with reflected damage, and the initial hit could be in an Ex mode but it wears off before a chase triggers.

Has anyone else seen something like this happen?