Access to URL via Archive-It redirect

Archive-It URLs like https://wayback.archive-it.org/org-350/https://www.nlm.nih.gov/exhibition/cesarean/index.html nicely redirect the user to the last crawl for a page, but sometimes this action fails and the result is the Archive-It "Not In Archive" page. This specific example fails.

However, when navigating to the list of of all crawls like https://wayback.archive-it.org/org-350/*/https://www.nlm.nih.gov/exhibition/cesarean/index.html the individual page/url is indeed available.

Is there a reason the internal redirect would fail? Both the collection and seed are public. The page is available in the pubic interface via search and browse.

We have ~50 of these failures out of thousands of seeds, so are confounded.

Thanks for any ideas,

John