What happened?
Summoned Magus Sisters - did Delta
Attacked with regular attacks until OD was full, then Delta again
Second delta did not count the damage, damage animation played but no damage dealt
Regular attacks also didnt count the damage
When sisters were dismissed, attempted to use party regular attacks, attacks did not count damage until a few moments later when finally it did.
Doesnt seem like an AP world issue, could just be vanilla game, but more testing should be done to attempt to replicate.