If you speak about the new Render Track option, then this is normal. Rendering only start with first clip. This is to handle the case where songs are staggered over multiple tracks. In that case, you want to skip the silent part.
This being said, without further notice, I admit this is misleading, and an option should rather be added.
This being said, you have today a workaround: solo the desired track and render the whole montage.