Hi, I have exactly the same issue, and it seems to be cam chain tensioner. I bought my car from Germany from authorized AUDI Dealer, then car has been brought to Slovakia and immediately after one week the strange sound started from engine. Here is the video. It seems to be bad chain tensioner or time chain. I will get check next week, nevertheless I hope it will be possible to push AUDI dealer to repay it ad this is hidden issue of the car. My car is 68k km only, 3.0 TDI
https://www.youtube.com/watch?v=rTXodiAThQ4
Thomson did you manage to solve it?