Audio not working in Camtasia, works fine in all other products

I have a bunch of Camtasia project files that I've created over the last few months and I can no longer play ANY of the audio files within Camtasia. The audio files all work fine if I listen to them in some other application. If I produce a .mp4 file, the audio works fine in the final file, but I need to be able to listen to the audio in Camtasia itself. My audio works perfectly fine in Audacity, on YouTube, on Netflix, pretty much any other application. I recently purchased a new microphone and the audio settings got a little wonky when switching between applications, but no matter what I do, I can't get my audio to work within Camtasia, and not only is it driving me crazy, this problem is screwing up my production schedule.

I'm using an HP Pavilion laptop with Windows 10 and Camtasia Studio 8.6.0. Can anyone help?