I have a four input USB interface. We used to be able to record all 4 microphones with the mono setting selected. We noticed that a couple weeks ago Audacity is only picking up the very first input and none of the others. I have trouble shot all i can and even used the tips on this forum for changing the setting in windows and i still cannot get it to work. Any suggestions. I am using the Beringher U-Phoria UMC404HD as an interface.
Try Windows audio hosts other than “MME” …
https://manual.audacityteam.org/man/multi_channel_recording.html
And 4 (mono) record channels selected …
https://manual.audacityteam.org/man/tutorial_selecting_your_recording_device.html