No audio on WhatsApp desktop

My colleagues and I can't hear audio on outgoing calls made from the WhatsApp desktop app on our MacBook Airs. The person on the phone can hear audio from the person on the computer, but the person on the computer can't hear the person on the phone. The audio works fine if someone calls from a phone and we answer it on the computer.

We have:

• Checked all the microphone, speaker, and volume settings on our computers and phones
• Rebooted our computers
• Uninstalled and reinstalled the app
• Closed all other apps in case they were interfering

Any suggestions for what we might be missing?