As a substance that floats on the water, I'd imagine the bulk of the liquid solar cover would be trapped in all the bubbles when you roll up the solid solar cover. It's not like it would step aside to not be in the way, then swim back to coat the pool surface again.
For lack of a better analogy, make believe it was vegetable oil. Some would wash off the cover and stay behind, but alot of it would go with the cover.