I have been using Audacity 2.3.3 fine for quite a while on pre-Catalina versions on a MacBook Air with a Technics USB turntable. Just yesterday, I upgraded to Catalina and Audacity 2.4.2 and am getting no recording volume from either my turntable or the laptop microphone. I can see that the laptop is getting the input signal. I am using the Terminal workaround that has been posted on threads for pre-Catalina versions but was under the impression that the latest Audacity release solved the problem. Any thoughts are appreciated.
The terminal workaround should no longer be necessary with Audacity 2.4.2, but Audacity does need to be granted permission to access the mic in
“System Preferences > Security & Privacy > Microphone”
Thank you. I had to re-download 2.4.2 and things seem to be working fine now.
Super 
Thanks for the update.