NetworkPolicy causes pods to enter CrashLoopBackOff or Failed states

Issue

• I have implemented what I believe to be the correct policy configuration for NetworkPolicy which is blocking horizontal traffic and allowing egress traffic
• However, it is not allowing traffic in via the ingress routers. This is also causing healthchecks to fail intermittently and the pods to crash.
• After setting up a Deny-All NetworkPolicy, pods keep crashing

apiVersion: extensions/v1beta1
kind: NetworkPolicy
metadata:
  name: deny-all
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          project: default
    - podSelector:
        matchLabels:
          type: ingress