On many LG phones there is one setting that creates issues with call recording.
Please go to phone settings and disable "Voice Enhancement" and reboot.
If there is no setting called "Voice Enhancement", look for any setting related call audio and disable them
Also, please remove any other call recording app
If on Kikkat, set recording folder to internal storage and also note that MP4 format might not work properly
Don't forget to increase your star rating once issue resolved :)