I got content_blocked

The engine declined the prompt, or the policy guard refused it. It is a code, not a lecture, and it is never charged.

The policy guard refuses anything that reads as involving a minor — an age under 18, a word for a child — in the prompt, a cast character's sheet or an element. It is deliberately broad; rephrase if an innocent word tripped it.
A third-party video engine applies its provider's own moderation and may decline intense fiction. Motion One, eroq's own engine, renders within the policy without that layer.
The negative prompt is never checked, so "child" there is fine — it excludes one.