How to record sounds from android phone to PO-33 KO?

So I was watching this tutorial the other day https://www.youtube.com/watch?v=T1841FR_eE8&t=761s and at 12:37 this guys connects his phone to the PO. I wanted to do the same, so I connected them with 3,5mm stereo cable, I tried out all the sync modes and wanted to record the sounds from my phone in all of them, but none of it worked. I pressed the record button and melodic slot and nothing was recorded. I even saw the same thing on the screen of the PO „IN“ and those small bars that indicate reception of the signal as in the video. What am I doing wrong? Please help, thanks in advance!

You don’t need to sync anything.
Plug the out of your phone to the in of your K.O.
Hear the incoming audio?
Weather or not your are recording you should be able to hear the incoming audio.

Now - When you want to record, get the audio on your phone ready, hold down record & the slot you want to record to (both need to be pressed down to record). Press play on your phone. It gets recorded.

Done

You say you see the small bars, but do you hear any audio?

Maybe wrong side used to plug the cable?
Try other side and set loud volume holding BMP and pressing some number.
I hope the author was able to resolve that on his own. No need instructions - just lock a man for 2 days with it and he’ll find out everything on his own.