If you didn’t change anything else, then the update most likely changed Windows Sound Processing. It could add processing you used to have, or stop processing when it used to.
https://forum.audacityteam.org/t/normalize/54779/50
https://www.youtube.com/watch?v=sxnUjiGgBaI&feature=youtu.be
Looking at the blue waves is nice, but hearing the work is even better. Post samples. Sometimes we can recognize the sounds.
https://forum.audacityteam.org/t/how-to-post-an-audio-sample/29851/1
Include some of the “silence” as well as the voice. You can go to ten seconds for a forum sample and sometimes longer is helpful.
It’s also good to know how you’re mastering for audiobooks. If that process stopped working, that can give us clues, too. Most times you can’t just read in the kitchen and post on-line.
Koz