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I did not find this hidden feature (someone on Facebook did and then I heard about it on Discord... what a world) but I think I narrowed down some of its functionality.
1) Go to the tape track
2) Hold shift and press the module track so it is lit yellow (the module track is the little "c" in the box)
3) Press play (the tape track and I think the module track need to be unmuted)
4) Tilt the OP-Z and press the screen button to activate the microphone and continuously feed it into the tape track
5) Have fun! As usual, press stop to capture a moment in time, feed other stuff into the tape and make beautiful layers!
Edit #1: Oh, I should mention, it also helps to have something sequenced on the tape or a key pressed so that the tape actually runs
Edit #2: spelling...(shit v. shift)