I am a novice…just need to remove vocals from a track, but when I follow the ‘split track’, ‘invert’ process everything is removed, including instrument. It is an acoustic track, vocal and guitar only. thanks for the help!
That happens when both left and right channels are identical - in other words it is a mono recording. Vocal removal requires a stereo recording with the vocal in the centre and the instruments off-centre. Vocal removal does not work on all tracks, and the track that you have is an example of when it does not work.
See here for more information: Missing features - Audacity Support