Beats Flex wireless left side mute

Hello Cesar Antonio,

It looks like you joined the Apple Support Communities from an excellent starting point; Sound troubleshooting – Beats headphones and earphones - Apple Support. Make sure when you reset the Beats, that you followed the steps under the section labeled "Reset Beats Flex."

1. Hold down both the power button and the volume down button for 15 seconds.

2. When the LED indicator light flashes, release the buttons. Your earphones are now reset and ready to be set up with your devices again.

Also, if you did not get a chance, you'll want to make sure the firmware of the Beats Flex is up-to-date. You can do so by following the steps here: Update your Beats wireless headphones or earphones - Apple Support.

To use your Mac to check that your Beats are up to date, make sure that you have the latest version of macOS. Press and hold the Option key while choosing Apple menu  > System Information. Click Bluetooth, then look under your Beats for the firmware version. With macOS Ventura, you can also choose Apple menu  > System Settings, click Bluetooth, then click the Info button   next to the name of your Beats.

The firmware update process can frequently address unexpected software behavior. If the issue remains after following these steps, you'll want to reach out to Apple Support directly for further assistance with this issue. You can reach out to them by clicking here: Contact Apple Support Contact - Official Apple Support or over the phone by calling the number that is most local to your region: Contact Apple for support and service Contact Apple for support and service - Apple Support.

We hope this information helps you out.

Cheers!