Ticking sound from engine

[Panny2014]

My journey with my Porsche Panamera has been very expensive. I had timing chain done, and other work done from dealer and sound still there. $10000 in repairs and that irritating ticking sound still there. Dealer suggested that the tappets/lifters could be bad but that comes with a $6000 tag.
Any ideas of what could be the problem let me no. The sound seem like it coming from the driver side of engine valve cover.