Anyone ever have issues when using Crank Bros Eggbeater pedals with Sidi shoes?

I got some Sidi Dominator 5 shoes and new Eggbeater cleats for them. I have them installed along with the Shoe Shields, (which are taller than the shims,) but the cleat does not engage with the pedal very well. I have to take my time and really push down hard before the cleat clicks into place.

I'm wondering if this is because of the hard plastic tread on the shoes. On my other shoes with an actual rubber tread, the Eggbeater's wings press into the rubber as needed, and everything is fine.