I recently updated from version 1.95 (because old version could not record new games) and encountered a bug that was never present before.
If I select "Disabled" in the secondary sound device list (in fact it is the default setting), somehow the effect is such as if I selected "Default sound input", and sound from my USB Logitech HD C270 webcam is mixed into the recording. It is definitely a bug.
The workaround is to disable the webcam in the list of recording devices in Windows, but it is very inconvenient.
Can you confirm it (reproduce yourself), and if you do fix in the next version? Mine is 18.104.22.1680