[FujiSkunk]

If the vocal track is indented under another track, that means it’s “inside” a folder track (the first track tat isn’t indented, above the indented track). If you have the vocal track unmuted but the folder track is muted, make sure to unmute the folder track as well.

If that’s not the case, you may get a clearer answer if you’re willing to provide your REAPER project file somewhere for download.