I've been trying for the last 3 days to setup cert-manager on a K8S cluster (v1.19.8) in an OpenStack environment with 1 master and 2 nodes. It worked before (like 1 month ago), but since I re-created the cluster, pod ACME challenges cannot be created due to this error:

Status:
  Presented:   false
  Processing:  true
  Reason:      pods "cm-acme-http-solver-" is forbidden: PodSecurityPolicy: unable to admit pod: []
  State:       pending
Events:
  Type     Reason        Age                    From          Message
  ----     ------        ----                   ----          -------
  Normal   Started       8m25s                  cert-manager  Challenge scheduled for processing
  Warning  PresentError  3m18s (x7 over 8m23s)  cert-manager  Error presenting challenge: pods "cm-acme-http-solver-" is forbidden: PodSecurityPolicy: unable to admit pod: []

I've tried different versions of the ingress-nginx, different versions of cert-manager, different versions of k8s, but to no avail. I'm getting crazy..., please help. Many thanks :)

Cluster setup

kubectl create namespace ingress-nginx && \
helm install ingress-nginx ingress-nginx/ingress-nginx -n ingress-nginx && \
kubectl create namespace cert-manager && \
helm install cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --version v1.1.0 \
  --set installCRDs=true

Issuer

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: letsencrypt-prod
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: email@example.com
    preferredChain: "ISRG Root X1"
    privateKeySecretRef:
      name: letsencrypt-prod
    solvers:
      - http01:
          ingress:
            class: nginx

Ingress

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: main-ingress
  annotations:
    kubernetes.io/ingress.class: "nginx"
    nginx.ingress.kubernetes.io/from-to-www-redirect: "true"
    cert-manager.io/issuer: "letsencrypt-prod"
spec:
  tls:
  - hosts:
      - host.com
    secretName: the-secret-name
  rules:
  - host: host.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: api-nginx
            port: 
              number: 80