All movies dated 06/06/1905

I am running Kodi 17.1 on a Firestick (Gen 1) from a Upnp source (using JRiver Media Center 22 running on Windows). The Actors, Director, Genres, etc. all work but ALL the files are dated 06/06/1905. I am guessing that Kodi is looking at some field for the date which is null in my setup, and that 06/06/1905 is essentially “time zero”. But I could be wrong.

Question is, WHERE does Kodi look for the date? Is it looking at some attribute within the Upnp stream? If so, WHAT exact attribute is it using? Perhaps I simply need to create that attribute on my server.

I’ve seen a few older threads about this with respect to a particular server, but never any resolution. I may need to fix this on the server end but I won’t know how to do it until I know exactly what the name of the attribute which Kodi parses as “Date” is.

Thanks in advance,