Diana/Hourglass Bug?

Had a game the other day playing Diana in the jungle. during the last fight of the game I jumped in and started hitting Ashe

I was about to die so I used 's active

at the time, I was on my 3rd Auto Attack and had Diana's passive charged. while I was frozen in stasis, Ashe was killed by my Passive ability even thought I couldn't attack

[I can't recreate this myself]