It seems that the artist / rightsholders or label have decided to make the album unavailable. There may be changes in licensing undergoing, or there are some other reasons.
You can try finding the artist's website or social media account and send them a question about this. The guys managing those sites should know what's up with the content and be able to offer a better answer. 🙂
Hope that helps!
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.