[GAMEPLAY] Tryn ult not working when he owns a GA

I just lost a game a few minutes ago due to an interaction between GA and Tryndamere ult. It went a bit like this; 1-Tryn would go into a teamfight with both GA off CD and Ult off CD 2-He would get reduced to around an AA of damage to die and ult. 3-Said auto would kill him but the ulti animation and sound queue would trigger, the ult would also go on cooldown. 4-After GA animation was done he just instantly dies. Idk if this is an intended interaction between the two. But it made all 5 of us lose the game hard. It happened about 4 to 5 times.