Hey there, in case you didn’t try it before:
If you’re mastering for vinyl, you need to eliminate stereo antiphases - especially in bass frequencies.
Use two instances of Pi in a modular DAW / VST wrapper and connect the left channel of the master sum to both inputs (left&right) of the first Pi and connect the right channel of the master sum to both inputs of the second Pi. Then connect the first Pi to the left master output and the second Pi to the right master output. The finished master signal will be a rich and present sounding stereo signal without any negative phases on the phase correlation meter.
Just so you know. I love the results.