Camtasia video 2020 fails to capture mic audio on long video

So I just finished a long recording (a lecture) on Camtasia 2020 on Mac. I was recording my microphone (Mac wired headset), system audio, and some slides. When I do tests, or shorter videos, everything works fine. 

This lecture was over an hour long capture ("4gb" according to Camtasia). There is system audio, but nothing from my microphone. Over the course of an hour I paused it twice, but otherwise, didn't do anything weird. 

The TREC file even says that "track 4" is "microphone." But nothing is recorded there. If I test it again, with the same set up, it works. 

Is there any hope of recovering my lecture, or is it lost forever? Did I hit a limit (4gb seems suspicious to me)? 

If this is a hard limit, it would be nice to know not to pause the recording, but to do multiple clips.