Working the strict movement on stable surfaces will help you learn timing and control on the muscle up.
Try stacking boxes up so you can practice the muscle in the hollow position.
Start with working on the forearm to a muscle up catch position on a box.
Then once that becomes easy and smooth try working the full arm to the muscle transition on a box again once this is a smooth transition move to the more dynamic movement on the rings.
You will see if you can pull and turn over on the rings you can also be working on a smooth kip motion on the rings. Working to keep tension from your toes to your hands to the rings and rope. If you lose the tension it becomes very difficult to turn over the muscle up and you end up catching it very low in the dip or not turning it over at all.