I2S setting using Denafrips Pontus and Iris

Hello, I'm new to this forum so I hope I am posting in the right place.
Can you help me please?
I have a Denafrips Pontus and I have just purchased as Iris. I may send the Iris back soon and order a Gaia instead. I have used a spare cheap Amazon HDMI cable from the Iris Out to the HDMI (i2s) Input on the Pontus.
I followed the instructions on the Vinshine youtube website:
I put my Pontus on to the i2s input.
I pressed the Mute button. the lights cycle.
I clicked the Phase button repeatedly.
On two of the "clicks" of the phase button I get sound but with terrible distortion.On all the other settings I am getting good sound.

Why am I getting sound from more than one of the "clicks"? I am not sure if one sounds better than the other yet but surely as the Pontus and Iris are both made by Denafrips then one of the settings I choose should be the correct one?

Also, would I get a better sound by using an HDMI cable that has the video pins removed? If not, using a standard HDMI cable, what would you recommend please? I can hear a big difference when using different makes of USB in my system so I assume a decent HDMI cable would be the way to go as well.
Finally, am I doing the right thing using i2s or would any of the other outputs on the Iris be a better way to go?

Thank you for your help.