Phase in RX7 is the shifting of the sound by mechanical means, in other words, for a brief instant, the left channel is getting more sound or sound quicker than the right or in a different direction. It is not the sound engineer's definition of phase, where the wave curves are opposite the ones in the other channel.
It is generally caused microphones are attached to the shoulders, the collar or the head and the taper moves his or her body causing the recording to be slightly out of phase. RX7 goes through a learning phase (no pun intended) to analyze the recording to determine if portions are out of phase, then adjusts the channels in very short intervals to increase the gain in that out of phase channel. The sensitivity, the amount of correction, and the time segments are adjustable in RX7.
This is an over-simplification, but I invite you folks to try it on a throw away recording, making 10 seconds facing the stage and 10 seconds facing left and 10 seconds facing right. RX7 adjusts for these otherwise imperceptible head movements.
I am no audio expert. But I learned this trick from the JEMs folks who literally do this on every audience tape. It works.