Phone call recording apps only record one side of the conversation

I have a Sony Xperia XA1 running Android 8 and it doesn't matter which phone call recorder I install, it only records one side of the conversation either me or the caller. All the apps do the same on my HTC Desire too. I'm not sure if it is the app at fault as they all seem to do the same thing, and this didn't start happening until I updated the Android version towards the end of last year. Does anyone know of a solution to this issue?