[100K+]

I had what I'd call the same issue you describe. Mine manifest itself when trying to do a three point turn in a back lane....I got actual bangs from transmission. Took me ages to resolve due to faulty initial diagnosis.
The issue was the DEM unit which controls the haldex. Initially givena clean bill of health,it was not until a member here suggested their diagnosis could be suspect i returned to suspectingthe DEM again.
This time sent it to Lucus @ volvodiagnostics who found odd fault in DEM which he could not repair, but could clone another DEM. Turn round was a couple of weeks but item as promised was plug and play. Circa £300 . I Ran the car (AWD R) for at least another 2+ years without further AWD issues. Have used Lucus for a couple of V70 issues as have others, once repaired it works and lasts..

Cheers Bob