Otter Butter will also keep the tip floating on a plastic line - most need the help. Many times I’ve had a greased furled leader dragged down by a sinking plastic floating line tip. The problem with the tips on plastic lines is the level or even-thickness core, which has a specific gravity lower than 1, isn’t sufficiently floated by the thinner-diameter plastic coating (with specific gravity less than 1) in the tip. So it’s otter butter, and archimedes, to the rescue.
John