Is LB gauge not resetting a bug?

Today it occurred to me that the limit break gauge not resetting between fights may not be working as intended. I tried to find a thread about this on the bug forums but found only three threads about limit breaks, none of them related to this.

So, sometimes when you wipe in an instance, the limit break gauge you had by the time of wipe resets to 0, sometimes it stays as it was and you're able to start the fight with limit break. Which one it should be and has anyone seen it in known issues / bug reports?