I'm working on a proof-of-concept on how to build our next website. One of the things we have been waiting for is Block-Level Variants in V15. It is now working as i would expect in the backoffice, but variant blocks are missing in the Content Delivery API. The V15 RC announcement mentions validation, tags and search index not working yet, but nothing about Content Delivery API. Is this expected to be fixed with the other issues?