Jellyfin: The Free Software Media System

I started using Jellyfin a few years ago as a shared backend for my Kodi boxes (CoreElec mostly but not exclusively). I use the Jellyfin plugin for Kodi, installed from the Jellyfin repo as per official instructions. I've stuck to defaults/recommendations in the plugin. I did this for the WAF (wife approval factor), because otherwise none of my family ever used it. Now I get a shared watchlist and can stop on one TV and resume on another.

I've been running into a problem, and after extensive troubleshooting, I'm at a loss and asking for help.

The Kodi boxes do not pick up new content when it hits my server, which happens fairly regularly as I am ripping my disc collection into a format that Kodi (and the little Arm boxes) support natively. Unless I restart Kodi or the Jellyfin plugin every day or so, they do not see any new files uploaded since their last restart and if it goes long enough, even watched status falls out of sync and I have to go through the lengthy process of resyncing that entire library.

If I restart my Jellyfin service, every Kodi box immediately reconnects within a minute but still nothing syncs unless I restart the client.

Is this a known issue (Google is pretty useless in this regard)? Is there an option I can change somewhere to force the check-in to sync on a schedule? Is there another plugin that would work and still show content "normally" in the libraries, as opposed to going into another screen? Or does everyone use the Jellyfin web frame client?

Thanks.