Can't record audio with external mic

[JarvisJo]

Hi

I have been spending the past week ordering items and trying out combinations to no avail!
My phone is the s20
I am trying to use an AKG microphone, via a scarlett 2i2 interface as audio input, and nothing seems to work.
At first I naively thought that I all had to do was plug the USB audio interface into the phone via USB: as some of you may have already experienced, it produces a horrible screeching sound!
So I assumed that it would work instead with audio cables, that I would plug into my phone via a jack 3.5 to USB-C cable, so I bought both of those, plugged it in and... Nothing.
After hours of searching I found out that I had to buy a signal splitter, to plug the audio cable into the mic female jack and that would then connect to the jack to usb-c via a TRRS jack... So I buy that...
And still nothing!

I read that USB audio player pro has a driver that can bypass the phone's USB driver, so I purchase it... I still can't record audio when I record a video! 
I have exhausted every options, find nothing else on the internet, and can't understand WHY IS IT SO DIFFICULT to just record USB audio with this device??
I must also tell you that

-all of this works perfectly with my previous phone the S10 with the audio plugged via the headphone Jack
-My headset microphone works fine when I plug it in via the 3.5 jack to USB-c cable, or when I plug it into the microphone jack of the signal splitter. So the problem doesn't come from the cable.
-When I try to record I can hear through my interface's direct monitoring the sound picked up by my AKG microphone through my headphones. So the mic works, the interface works and sends the right signal. But that is still not the audio signal recorded by the phone! 
-When I press record on the phone, I get the notification "recording audio through headset", so it DOES detect my microphone but then it still record audio through the built-in mic. WHYYY??
What do I need to do, to connect my audio interface to my phone and get it to record the audio that comes from it?
I feel like I've exhausted every possibility, and I can't believe that there wouldn't be a solution??

Thank you very much to anyone who could help.

[BeeeBeee]

I use a Comica AD2 converter box to pro video setting, works a treat and u can control record level from the box. Can send photo of my setup if u send your email address 

[walkin]

I am using Focusrite interface, and connected with a USB-C adapter (with HDMI, USB ports and power in USB C port). Anyway, for me there isn't a workable solution unless I lower down the mic volume to the lowest. The screeching sound immediately disappears. However, if you speak too loud, it comes back. I am suspecting is the power supply from phone to the interface is too high for the device.

FYI:

I have removed the power input (charger cable) to the adapter, hence power is supplied solely from the phone, still the same screeching issue.

So I believe its a the phone. 

[BeeeBeee]

you can record broadcast quality sound from your phone if you use a Comica AD2 LinkFlex Box. I use professional mics via an xlr plug but you could add a converter lead to mini jack