So I completed all the missions from a specific active medal. When I go to Select Medal I can see everything with a tick, what now?
From what it looks like, the medal system is nothing more than a way of keeping players active and a way of awarding active players XP.
I have seen nothing about actually displaying these medals or anything about the purpose of the medals beyond an xp reward system.
The ticks displayed are most likely a way of notifying the player that they have indeed completed the requirements for the medal in question.
If I see anything I'll update my answer and keep you posted.
I hope this answers your question