Yeah for me it started with one ui 4.1 in my note 20 ultra as well and hasn't been fixed till now. Anyways I have good coverage where I live so it doesn't bother me. Have tried other call recording apps as well but samsungs inbuilt one was mist conve...

It won't record if call over WiFi is enabled and you are connected to WiFi. That's how mine behaves so once I switch off calling over WiFi it will work again