rtv said:did you misleadingly tick the default language option?
Force Subtitles (overrides disc defaults) is not used and for Subtitle language have tried both invariant or French/English.
Apparently the bug exists only when you have two streams with the same name. And when you choose the second one. It will revert to the first one on chapter change.
1:Japanese, 2:English will not produce the bug. But
1:Japanese
2:English
3:Japanese
will bug if the user choose 3:japanese.