Figured I'd post this to possibly spare others some pain.
I was having trouble getting Zotero to save my COinS items--not discover,
just save. Like the little note icon would show up in the location bar but
when I clicked it nothing got saved.
Anyway, I think this is what was happening: when parsing the ctx object
Zotero looks for the presence of an rft.stitle or rft.jtitle attribute to
determine if the itemType is journalArticle. But I think it's not checking
if there's an actual value. So if you have "
of Blah Blah&...." then Zotero stops at the stitle param and proceeds to
try and save the entry. So the moral of the story is watch out for empty
OpenURL attributes in your COinS.
Much thanks to rsinger for I would not have stumbled upon the solution
without the umlaut's COinS for the same citation for comparison.