Audio may not record if the microphone settings are incompatible. Here are the steps to check and adjust these settings:
- Click on the Spotlight Search icon, type "audio midi setup" in the pop-up, and select Audio MIDI Setup to open the utility:

- In the Audio Devices window, select the microphone or webcam you use for recording:

- In the Format section, set the sample rate to 44,100 Hz:

- Reboot your computer to re-initialize the microphone in the app.
If that fails to resolve the issue, you may need to update your Permissions. This article walks you through how to do so: