You'll need to methodically work through the signal chain to solve this one. It could be
that something in your audio interface's mixer that is routed back to the inputs to your
DAW. I also frequently see this happen when people use external hardware mixers, since the
routing is misunderstood. If you overdub any other tracks do they also contain the other
audio you're monitoring? For example, if you track a bass, then does the previously
recorded guitar end up on the bass track too?The 'disappearing metronome'
is something I've had for a long time now with Cubase - it's certainly still happening in
the latest version and shows no signs of being fixed from what I can ascertain. I've
pretty much given up on it and habitually load up a simple drum pattern to work to.
An Eagle for an Emperor, A Kestrel for a Knave.