I use ActivePresenter for several years now on my Mac and I never had problems using Logitech ou Plantronics usb mic.
But yesterday, I made an update of ActivePresenter and I’m no more able to select usb mic.
I can use build-in mic, but the usb microphone appears in the System audio (see pic below)
ActivePresenter Version: 7.5.2
OS: MacOS 10.14.2
I hope you will be able to solve the problem.