Steam Achievement Explore Owl's Head Broke

1. Title: Steam Acheivement Explore Owl's Head
2. Reproduction Rate: 100%
3. Blocker? No
4. Details: If you didn't get the Explore Owl's head achievement while the Lunar Rift in Owl's head was active/ discoverable as an interest point, it is now impossible to to earn the achievement, stuck at 11/12.
5. Steps to Reproduce: Use new Steam account, Go to Owl's head, got to all the Points of interest, Run around the lunar rift area and fail to discover it as a point of interest.
6. User Specs:

 

Can I get confirmation that either, This was a limited time only acheivement that is no longer available, This is a bug and the acheivement will be updated or the area made discovrable again, or that there is a new area of Owl's Head to discover to take the place of the Lunar Rift for the 11/12 completion and I'm just not looking hard enough