The thumbnails on the "on now" tab of the app are broken, except for a few, generic station logos.
They are broken on the iOS app, on the web interface, and the FireTV app.
The 2-week guide is intact.
My server is run on a Synology NAS.
The only thing that could remotely have caused this was removel of the UPnP in favor of manual port forwarding, but I doubt this was the reason.