Playback problems are usually a Safari issue, switch browsers. And note: muting keeps a track in the mix, set volume to 0 to remove it.
This is a known issue that mostly affects the Safari browser. If you're on Safari, switch to a different browser such as Chrome, and playback should work as expected. On mobile, also check that your phone isn't muted at the hardware level.
Muting a track doesn't remove it from the mix. It stays included in the processing. Mute is a monitoring toggle, not a way to exclude a track from the final result.
To fully remove a track from the mix or master, set its volume to 0 instead of muting it. At zero volume, it won't be audible in the final mix or master.