I went through a similar nightmarish front clunk chase ...... thought it was the radiator (clunk was replicable just with tap-braking), checked brakes/pads, radiator, engine mounts, etc etc etc
https://xoutpost.com/bmw-sav-forums/...tor-loose.html
After weeks of chasing the culprit, replaced lower control arms -helped but did not completely removed the clunk- I believe the issue is still the #8 part in the diagram which plan to address soon.