I’m running LMS in docker as well, although on a separate server. Where do I find the "Save-media_player.[LMSPlayerName] " playlist? Here’s the logs:
2021-07-23 11:23:30 DEBUG (MainThread) [custom_components.lms_tts_notify] Received on event bus: {'entity_id': 'media_player.kitchen_radio', 'message': 'Test', 'volume': 0.8, 'device_group': 'person.pat'}
2021-07-23 11:23:30 DEBUG (Coordinator) [custom_components.lms_tts_notify] Save state: media_player.kitchen_radio -> {'state': 'playing', 'attributes': {'volume_level': 0.5, 'sync_group': [], 'media_position': 21, 'repeat': '0'}}
2021-07-23 11:23:30 DEBUG (Coordinator) [custom_components.lms_tts_notify] Save state: media_player.bedroom_radio -> {'state': 'idle', 'attributes': {'volume_level': 0.2, 'sync_group': [], 'repeat': '1'}}
2021-07-23 11:23:30 DEBUG (Coordinator) [custom_components.lms_tts_notify] Save playlists: media_player.kitchen_radio
2021-07-23 11:23:30 DEBUG (Coordinator) [custom_components.lms_tts_notify] Save playlists: media_player.bedroom_radio
2021-07-23 11:23:30 DEBUG (Coordinator) [custom_components.lms_tts_notify] UnSync media_player.kitchen_radio
2021-07-23 11:23:30 INFO (MainThread) [pysqueezebox.server] Query run on unknown player 00:04:20:1f:00:6f
2021-07-23 11:23:30 INFO (MainThread) [pysqueezebox.server] Query run on unknown player 00:04:20:26:26:ae
2021-07-23 11:23:31 DEBUG (kitchen_radio_queue) [custom_components.lms_tts_notify] Playing message 'Test'
2021-07-23 11:23:33 DEBUG (kitchen_radio_queue) [custom_components.lms_tts_notify] Waiting for media_player.kitchen_radio to finish
2021-07-23 11:23:33 DEBUG (Coordinator) [custom_components.lms_tts_notify] Restore volume: media_player.kitchen_radio
2021-07-23 11:23:33 DEBUG (Coordinator) [custom_components.lms_tts_notify] Restore state: media_player.kitchen_radio -> {'state': 'playing', 'attributes': {'volume_level': 0.5, 'sync_group': [], 'media_position': 21, 'repeat': '0'}}
2021-07-23 11:23:33 DEBUG (Coordinator) [custom_components.lms_tts_notify] Restore playlist: media_player.kitchen_radio
2021-07-23 11:23:33 DEBUG (Coordinator) [custom_components.lms_tts_notify] Restore media_possition: media_player.kitchen_radio
2021-07-23 11:23:33 DEBUG (Coordinator) [custom_components.lms_tts_notify] Players all done: {'media_player.kitchen_radio'}
As a side note, Restore media_possition has an extra “s”.