Rancher 2.3 - Deploying Istio on GKE - ImagePullBackOff

After 2.3 became GA I used it to deploy a GKE cluster - as usual, all went well.

However, after I deployed Istio with the default settings, I was no longer able to deploy new applications, pod deployment would fail with ImagePullBackOff and a 503 server error while trying to download the image.

As soon as I disabled Istio, everything went back to normal.

I kept the defaults in the Rancher Istio deployment - any idea what I could have down wrong?

Thank you!