Tryndamere death while in mid ult (Gameplay)

I am not really sure how this bug is connected between Rumble's Flamespitter and Tryndamere, but I had to examples in a ranked match (Bronze V) :P where I would use my ult as Tryndamere and i would die after 2 secs if Rumble was still attacking me with his flame spitter. I am not sure how to get video evidence, but i just finished the game and if there was a way for you guys to look at the replay in the game you will see what i am talking about.

For example -

I was purple side in the blue side jungle by red buff. I was at half heath at the time and decided to chase a low health Rumble. I was going to the bush when he started to fight me. I popped ult, and the since i am supposed to stop at 1 hp, i continued to fight him. 2 seconds into the ult I died due to Rumble's Flamespitter. The second time it happened was at my mid inhib/tower.... same situation where i died because of Rumble.

Thank you for your time and i hope it gets resolved