Ford Sync 3 Problems

My 2016 Ford Focus has an intermittent problem with the Sync 3 sound system. Sometimes when starting the car the sound system will emit a very loud static/white noise sound from the centre speaker and turning the volume up from zero just increases the noise and no audio output from the other speakers in the car.

If I use the sat nav, the audio from this comes out of the side speakers without any issue but as soon as I turn up the volume on the dash the interference noise wipes out all other sounds.

I have found in the past that leaving the car overnight will often solve the issue.

The video below recorded on my phone shows the sound issue.

If anyone else knows how to fix this, please let me know in the comments below.