New Post: Error "Failed to get page template by id"

Not quite - The template is listed under Layout.

For some reason its not showing in Content page - template selection.
The page which has the new template allocated in dev - errors both if you try browse or in Content "edit" of page.

All other pages work. Just new page and template copied over from dev seems to be the issue.

I have checked matching id's, still checking each file associated with it.