Tahm Kench W bug when worked with Jayce E

I was in a Draft Pick Normals game playing as Jayce against a Tahm and during a fight I jumped on to him with my Q and E'd him away just as he used his W to devour me. That for some reason let the Tahm eat me and walk away at full movement speed back to his own turret leaving me directly under his turret and forcing me to flash away (which eventually led to me getting killed by their jungler) . Tahm W is supposed slow him to 95% of movement speed and I didn't believe there were any special cases in reverting the slow. I hope this can be identified and fixed as soon as possible.