If I use it in custom html module with Articles - Newsflash module aside it works, but if I disable Articles - Newsflash module I get error "WebAssetManager is locked, you came late".
That error will appear if you have things trying to add scripts or styles to the page, after the head section of the page has already been rendered.
If you are using Articles Anywhere inside a custom module, make sure the 'Prepare Content' option in that module is switched on.