Hello WineWanker,
From your post it appears that your MacBook Air is not sending audio to your Beats.
Toggle the selection to another device and then back to the Beats. This can sometimes reset the connection.
The article you came from, Sound troubleshooting – Beats headphones and earphones, has some solid troubleshooting for your Beats.
Have you tried pairing a different set of Bluetooth headphones to the Mac? This would help determine if the issue is with the headphones or with the Mac.
We would also try pairing the Beats with a different device to confirm that they work as expected.
If the problem seems to be isolated to the MacBook Air, we would start by powering it off, and then powering it back on. While simple, this can refresh the macOS, apps and connections.
If the problem remains after restarting, we would suggest creating a new user account and testing to see if the same thing happens: Set up users, guests, and groups on Mac - Apple Support
If everything works in the new user, then you can concentrate on finding what in your regular account is making this happen.
Have a good day.