Your last bit about instruments vs vocals being out of phase with each other in a given track is something I didn’t dare mention for fear of scaring the OP. A good reason to just pick a polarity and live with it unless one has a preamp with a phase switch that permits convenience in choosing absolute phase per each recording.
Years ago I ran a blind test of my wife, my then teenage son, and a friend, using the phase switch on my Atmasphere MP1 and listening to my full range Sound Lab ESLs. I stood behind them, out of their fields of view, and flipped the phase switch on several recordings. Neither they nor I could hear any effect.