Renekton shield break vs TK

So I'm not sure if this is on purpose or? But the shield break mechanic with renekton, doesnt work against the Kench's E (thick skin).

It was my first time in that match up since the changes and thought perfect if I can hold onto some rage and hold my W I should destroy this match up.

Too my dismay, the shield was not broken and he ate the dmg and me like a Champ.

Was this intentional or is it a bug?