There is a fine line between "the polish going clear" (but still wet) vs. dry buffing. Besides, polishes behave differently. When a polish goes clear, it won't be totally transparent, just translucent. It does mean that it will be clearer than the milky state you begun with.
OPS is almost invisible at all times.

There are materials that seem to "disappear" from the surface or "melt into" the surface.
Never mind, just be sure that a wet polishing film is always present between your pad and the surface. Dry buffing causes swirls - that's absolutely true.