Install Operator on OKD - "no kind "AdmissionReview" is registered for version ""

Hello there,

I have an OKD 4.8 cluster and want to install/configure the current runner operator (1.6.1) as described in

Everything works fine until creating the CRD (last step). When applying gitlab-runner.yml, the manager throws an error:

ERROR	controller-runtime.webhook.webhooks	unable to decode the request	{"webhook": "/validate-apps-gitlab-com-v1beta2-runner", "error": "no kind \"AdmissionReview\" is registered for version \"\" in scheme \"pkg/runtime/scheme.go:101\""}*zapLogger).Error

and the runner is not registered, obviously.

Can you give me a hint?

Kind regards,