*Naninovel Version 1.15.
*We have 2 voice options, Japanese and Chinese. And we have 5 text languages.
*We use addressable for scenario scripts and voices. (Auto-Voice)
*We setup the text language dropdown when start game. (Detect player's locale language)

Some new players said they can't hear Japanese voice, but can just solve this problem with below step.

1. Select another text language, like English, Ch-TW, Ch-CN, etc... (Voice language is still Japanese)
2. Select text language to Japanese.
3. Start new game and they can hear voice.
   These step just need to setup once time, after that, players can hear Japanese voice in whole game, even restart the game, the voice also works.

It seems like some resources not loaded correctly or we just use some features incorrectly.

https://imgur.com/a/jPgDeW6
https://imgur.com/a/rJhSEWt

I was unable to reproduce this error using the latest 1.18 pre-release (available in Discord Support), as in I was able to change the voice language without needing to restart. If you are using custom C# scripts for the settings, I suggest comparing them with the default settings script (GameSettingsLanguageDropdown.cs and GameSettingsVoiceLanguageDropdown.cs). Otherwise if you are using a much older version of Naninovel I suggest updating to at least 1.17 (package manager version) as it's possible this was fixed somewhere along the way.

Thanks. We will try to update it and observe for a while.
*It happened randomly and just happen for few players, so we cannot provide the problem accurately :(

You could try enabling Development build and see if the player logs (https://docs.unity3d.com/Manual/LogFiles.html) gives any output.