Open Library IDs are case-insensitive in that their casing does not bear information, but the server requires the ID to be passed in uppercase: https://openlibrary.org/b/OL38581116M is a book, while https://openlibrary.org/b/ol38581116m is a 404. However, all (?) Open Library URLs that appear on ORCID web pages seem to be in lowercase, thus 404: see e.g. https://orcid.org/0000-0003-1199-7080.

This seems to happen because when the URL is generated from an ol-type work ID by the resolver service, it is passed (among other things) through org.orcid.core.utils.v3.identifier.normalizers.CaseSensitiveNormalizer, which is under the impression that case-insensitive identifiers entail that the URL can be harmlessly lowercased:

Open Library has a different opinion of what the normal form of the ID (and therefore URL) should be.

As far as possible solutions are concerned, either the case sensitivity flag needs to become a tristate (uppercase, lowercase, preserve); a further normalization step that fixes the casing for OL links needs to be added; or declaring Open Library IDs to be case sensitive. All of these seem a bit meh. Neither deals with the fact that there are plenty of wrong URLs already stored in the database (they are stored, right?).