2012 Phaeton Random Ding

We just purchased a 2012 40ft Phaeton with just under 70k miles. It dings an alert randomly, with no warning or light indicating the issue. Everything looks fine on the dash. The ding plays over the music (dimming music when it alerts) so we can’t find where it’s coming from. Everything is working properly, seatbelts clasped, awnings tight, etc. Only dings when driving, not at idle.

Any thoughts?