Tham and Shaco bug

Yo. Was playing a ranked game where I played as the support and had a jungler as shaco. i ate all of my allies to save them from CC but it never worked on Shaco. I tried and tried. but nothing happened. I literally spammed W over him when he was standing still and then with a light touch on the W key i ate my allie. tried this in custom. same thing there. cant eat shaco.