Parallax Occlusion Map Feature fails to render self-shadows as of the release of Unreal Engine v4.24.0 and has not been remedied since. The feature is perfectly functional in v4.23 [See attachments to compare]
Expected: Parallax Occlusion Map Feature should render self-shadows in Epic's own examples and with user-made materials.
Results: POM self-shadowing does not render.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-89838 in the post.