Due to some issues on 3.9.3 database migration, users were experiencing corrupt database or inability to connect Kodi Leia 18.5 installations to MrMC MySql database. This should be fixed now in 3.9.4.
Downmixing LFE into stereo as per user request on our forum https://forum.mrmc.tv/viewtopic.php?f=15&t=5235