Hello DJI!
acc. to your manual, focus track is deactivated when using ND-filters.
Can you confirm this?
I have not yet tested it.

Thanks, Uwe

It does clearly state this in the manual.

The camera needs as much light as possible even more so when pointing down at the ground so that it can pick out the target. As an ND filter is in fact sunglasses, this can cause an issue for the camera tracking the subject.

Hi there. Thank you for reaching out. Yes, the Focus track is disabled using when using a wide-angle lens or ND Filters. You may refer to the image below. Thank you for your continued support.