It's not just us. A number of practitioners here in Canada have reported similar behaviour.
We have deleted old versions and reinstalled Sonant 1.2.3 many times. The hardware is a new MacBook Air, 2020 model. It was recently upgraded from an old MacBook pro running High Sierra where Sonant worked fine.
Not only does Sonant not respond to push-to-talk (the lips don't turn red) but does not allow configuration of the push to talk key (which defaults to command). It ignores all key presses, leading me to believe it is not properly sensing the keyboard.
Curiously, the lips will turn red when using volume or SNR sensing, rather than push-to-talk, again telling me there is something wrong with your keyboard interface.