One airpod may not working due to the low battery, dirt, bluetooth issue or any other common connection glitch. Try to clean, charge, reset and reconnect it by turning off and on the bluetooth.
The One AirPod Not Workingdevicefixes problem normally occurs because of dirt accumulation, low battery life, Bluetooth errors, and software issues. According to devicefixes, there is always the possibility of dirt blocking the speaker meshes in the earpods. Furthermore, inconsistent charging could result in only one earpod failing. Connection problems between the two devices and your phone could also result in one airpod appearing as if it is nonfunctional.