Diana damage numbers

I havnt used diana in a while but I just used her and I can almost guarantee some mixed up damage. I dont know how often this occurs but something was off. I did take resistances to account like runes but things still didnt add up.

Ill just use this scenario as an example as it would be simpler. my ult at this time was to deal 160 (+100) (I think) magic damage. The enemy ashe was nearby and I used my ult on her, but the damage number that showed was 21, instead of what shouldve been much more. Even worse is that she actually only took this 21 damage, her health bar dropped minimally. After further looking into it I saw almost all of my abilities damage numbers werent adding up. Like my Q and W. As a result I was dealing a laughable amount of damage.

Again idk how often this bug occurs but it did just happen to me. It's probably a very rare thing I havnt seen a post about it.