SCC applied but doesn't appear to be taking effect

[ALL-SPACE-Anas]

Hi,

I'm new to working with SCCs so very confused with the inconsistent behaviour I'm facing. We have a bare-metal OKD4.15 cluster deployed. I'm facing this issue as part of my attempts to deploy and make github actions runner controller work (as it's not supported for OpenShift). I've managed to deploy it without hiccups but for runners, I've noticed, they need anyuid permissions (otherwise I'd get CreateContainerError because of Permission Denied on scripts). To resolve this, I provided anyuid scc to the service account associated with the runner pods. Used below command for it,

oc adm policy add-scc-to-user anyuid -z <sa>

I expected the service account to show up under "Users" but it didn't.
oc describe scc anyuid

Name:                                           anyuid
Priority:                                       10
Access:
  Users:                                        <none>

But I could see the pods being created afterwards so looks like it was effective. Now, I got into some errors working inside the pod and to rule out the possibility that it's not to do with the permissions, I decided to try with the privileged scc instead. So, used the following commands,

oc adm policy remove-scc-from-user anyuid -z <sa>
oc adm policy add-scc-to-user privileged -z <sa>

Service account still doesn't show up under Users when doing oc describe scc privileged but I expected it to be effective, which I suspect it was not as I start seeing the original error of CreateContainerError because Permission Denied. This hints to me that privileged scc may not be effective.

Another test I did was create a custom-scc which is basically the same as anyuid except it has "Allowed Capabilities: SETFCAP".

oc describe scc custom-scc

Name:                                           custom-scc
Priority:                                       <none>
Access:
  ...
Settings:
  ...
  Allowed Capabilities:                         SETFCAP

I added it to sa using the same steps above, but I keep seeing the same error of CreateContainerError because Permission Denied hinting that the custom-scc is not effective dispite it being almost the same. Could this be a bug? Is there something I'm missing?