I've seen mention of this a few times over the last few weeks so it was probably fixed a while ago, but /u/reylee did some testing for me directly just now.

You might remember a few months ago when Nyami came out I did some testing with her and found out BB ATK wasn't working for her single target damage because it has consecutive usage bonuses, and that was also affecting the damage of other units with that damage bonus such as Ravenna or Reviora.

This bug has since been fixed in JP BF, meaning that BB ATK buffs and passives will function for that type of unit.

The bug is still present in global, also tested in the current version of the game.

Even though Alim told Gumi the not working behaviour was intentional... well, whatever.