Please check the known issues list before posting a bug. apparently not there.
Platform, device version and operating system
PS4
Screenshot or image
i could potentially take some but it would not prove anything to be honest.
What you were expecting to happen, and what actually happened
_I used Elven Bard skill on Princess Fizzbang and later in another match on Nobend Brothers.
Instead of enchanting them and giving 2 magic, the enchantment dissipate after a singke turn and the magic remains to the saml value. Moreover, the buff/debuff icon for magic seems to randomly switch between each other (Either shows buff or debuff) on use of elven bard. At the very least I get the mana. 
_
How often does this happen? When did it begin happening?
First time I use elvend bard. I played multiple matches in divinion field and always get the same result.
Steps to make it happen again
I am not entirely sure. I tried with another team comp and it worked fine.