Each province has a two stages to completion. Discovery and Encounters. That the first needs to be done, and can be done is designated as "unlocked." If it's unlocked it has a spyglass on it, surrounded by a ring colored with it's difficulty. If it's Locked it has, naturally, a lock on it. (The blue arrow points to it). But before you can scout it, at least one province next to it has to be unlocked, scouted and then "completed" The province next to the locked one is not yet completed. It shows the icon of the type of province it is. The red arrow points to a crystal province.
Technically, in my opinion, the second (red arrow) province is unlocked, but since it's not yet completed, it locks the blue one. When I first started I thought once you "unlocked" a province it was done. Took a long time to realize that really "unlocking" (meaning, to me making it completely useful) is a two step process. Scout and Encounter. And I've heard the term "unlocked" to mean both or each. So this is just t clarify. Have you not only scouted, but also done the encounters in the provinces next to your marble one?
AJ