You should also check that accessibility service is on and other audio sources in Standard API's settings. Perhaps, you can unlock system recorder somehow as some Samsungs allow it: https://skvalex.org/help/system-recorderSamsung Note 20 Ultra here, brazilian edition, standard ROM, not rooted, running the latest Android 11 / One UI 3.1.
All recorded calls are silent, already checked the majority of the options there - none of it enabled to record the calls with sound.
I remember it was in the past an issue regarding the Android requirements, but I have no idea if this was fixed or bypassed somehow.
Any clues, folks?