Can Audacity Record VoIP Conversations, or not?

The answer is the same as it’s always been - you can only record Skype from stereo mix if you find a way to send the mic input to the playback device. You can do it by setting “Listen to this device” for the mic in Windows Sound (in Windows Vista and later), but it is a bad idea, and there are too many limitations and things that can go wrong.

Use an application meant for recording Skype, such as these How to record skype calls on audacity - #2 by Gale_Andrews