Same issue on my side. None of my iOS devices would play live TV (applets’s, iPhones). I reverted to version 1.13.8.5395 and all works well again (and I’ve now turned off auto updates).
For reverting to older version, at least on windows, all older versions are stored in ‘…AppData\Local\Plex Media Server\Updates’ - just uninstall the old version through control panel (all settings remain intact) and install the desired package. It’s pretty quick, but it would be nice if automated.
