Does an "automatic policy" start blocking right away?

If a security policy is in blocking mode there is the possibility that ASM may block some traffic right from the start. While attack signatures and allowed entities (file types, urls, etc) need to be enforced (staging disabled) before ASM will block related traffic there are other elements in a security policy which have no staging capability. Examples: RFC Compliance violations, allowed HTTP methods, allowed response codes. If these violations are set to Block on the Blocking Settings list and the Enforcement Mode=Blocking then ASM will block traffic that triggers these violations.