We expected that volume and issue numbers would be included in the article metadata submitted to Crossref, but they are not. The issue metadata includes this information, as well as a publication date.
I hope the problem isn’t the checkboxes at the bottom, since they determine what is written the top of the table of contents of the issue and on the landing page of every article, which is quite a different function.
Thanks, you are quite correct. Frankly I think this is a bug, since we should be able to customize the appearance of our pages without breaking DOI submission.