?
We have reproduced this, and determined that it has to do with the way nuget.org handles casing. If all lowercase (Id='jquery.cookie') is used, then results are returned. This is because we currently handle these types of queries by just translating them to use a filter instead (Id eq 'jQuery.Cookie'), for compatibility with older servers, and it seems that the 'eq' operator is always case-sensitive on nuget.org.
We may not need to be doing this translation at all anymore, since it's been a while since that new syntax has been introduced, but for now we will make a change to wrap this type of query in a tolower() odata function, which we have confirmed fixes the issue with this package. We'll include this fix in the next maintenance release.