Found the problem at my end, it was bad header data delivered by a new translator update channel for Juris-M. In the course of following up, though, I discovered that the Zotero channel is delivering configOptions both as an attribute and as text content to an eponymous tag. It looks like only the latter is read off by the client.
Bibliontology export: D837271324
RDF export: D1271896706
configOptions
both as an attribute and as text content to an eponymous tag. It looks like only the latter is read off by the client.