i just got my 9th medal and went to the medal screen since a long time. I can understand now where the idea of a 10 pull with medals comes from, there is a second button. But it isn't a 10 pull like with jewels, it's an "all your medals pull", in my case it was a 9 pull. I looked at the description then (the screen you linked), and on that tab as well as on the other tab it says, that in contrary to a jewel 10 pull, you are not guaranteed a SR or above with a 10 pull with medals. My Japanese is far from perfect and i couldn't say with 100% certainty, but it checks out with what Himitsu wrote.
Btw i also noticed that the medals expire after a week, they get marked in the medal info screen though when the expiration date is "near" (my oldest medal before the draw was marked because it was about to expire in 3 or 4 days)