Earlier today, I got this random item that allowed me to play this. And no, I’m not asking for hte answer btw. But now i can’t play this level. Why is that? Now i have to subscribe to play it. 
The dunes is a subscriber only level and if you are not a subscriber you should not be able to access the level
If you are not subscriber you might have accessed on accident and vice versa for if you are a subscriber
i got the same problem with another level on time. Iplayed it, without having sumbscribet and after i wanted to trie again, its now a subscriber level.