Playback issues since new update

Unfortunately, that is incorrect. The last public release was: Plex Media Server 1.17.0.1841

The version you have installed is a beta release per: Plex Media Server 1.18.0.1846 is available to PlexPass users in the Beta update channel

The current beta release is: Plex Media Server 1.18.0.1906 is available to PlexPass users in the Beta update channel

I’m not sure how a beta release was installed but it’s what you have currently.