Be sure to read https://yatse.tv/wiki/debug-yatse-kodi-remote to provide necessary logs and information.
When I first purchased Yatse (2019-11-29), my offline files would sync back with Plex when I stopped playback. If I wished to continue viewing that content on another device I was able to pick up from where I left off. I noticed a week or 2 after the purchase the Yatse was no longer updating the playback information of my files to Plex. Does anyone have a solution for this?