I currently have the same issue as well, I tried using audacity to record voice while recording footage, but I can't seem to get a hotkey to work for it without having the window currently selected, meaning that I have to start it and then hyper cam. Then if I want to end a recording I have to select the window again and stop audacity, and then hyper cam, or vice versa, which leads to a lot of guess work on trimming.
Without the microphone in the mix it will record even 15 minute segments without any degradation in the sound at all. But, with microphone input the issue kicks off around 7:10 as well. Strangely the microphone output seems to be clear, but, the system sounds (Like from a video game) tend to run choppy.
If anyone knows of a microphone recording program that I can set to record while in a full screen program with a designated hot-key, I'd quite like to know of it.
I will also try the beta linked in the description to see if that fixes the issue.