Lane Assist Not Working?

[Turbo Tony]

Since the accident repair, my lane assist LEDs in the wing mirrors haven't lit up once. Granted, I've been keeping well away from other cars, but they usually light up dimly when there's a car overtaking me and then flash like crazy if I indicate and there is a car in my blind spot.

There are no codes stored in VCDS and I can still use the MMI to set the brightness of the LEDs and they light up with the corresponding brightness.

Is there a functional check I can do with VCDS? Other than indicating like a madman on the motorway, is there any way I can test them? If faulty, how do I fix it?

The rear bumper (where I understand the radar sensors are located) was not painted, although the nearside rear quarter panel was.

I'm grateful for any ideas.