We check the index status for the backlinks when we add them in your account, and then automatically re-check them every month. It sometimes happens that the link will get indexed by Google in the meantime, which is why you'll see a difference between what MB shows and the real index status. To help you easily verify if the status is correct, you can click on the Google icon:
You can also manually trigger a reindexing by selecting the link and clicking "Recheck":
Please note that domain authority has nothing to do with a page being indexed by Google or not. A big domain can create pages that are not indexed.