Ekko no shield vs Tahm Kench

I been playing a boat loud of Ekko games, when I ran into Tahm Kench. Tahm devoured me walked into my circle and was stunned, but I did not gain a shield. Is this intended? The ability clearly states If Ekko enters the sphere (Doesn't say how), it detonates, shielding him for 2 seconds and stunning all enemies inside for 2.25 seconds. In order for Tahm to be stunned wouldn't I have to be in the circle what is one with out the other its a combo right? TLDR- NERF TAHM