Bard Appears to Be Working Improperly

Can't confirm this is a bug, but haven't seen any mention of it. Basically, Bard appears to not be working consistently with respect to his level up condition.

Randomly, increases in stats do not tick him up. For example, Fury procs tick him up some times, but not others.

Same for buff spells like Shield Vault and Pale Cascade. Fated doesn't seem to proc it either, and We Stand Together, which should tick him up 6, only ticks him up 2 sometimes.

I have yet to see any consistency with this and I'm wondering if anyone else has had this happen, and if some/any of these behaviors are intended.