My 2014 R1200GS LC has had a metallic click from new. When warm it was quite distinctive. No obvious cause but annoying and the techs at Motomart couldn’t solve it. 40,000 km later BMW NZ has produced a modified exhaust cam. It’s the decompressor mechanism and an immediate fix under warranty even though my bike is outside it now. Very happy.
Had exactly the same thing with my 2015 GS. Motomart picked up the fault at the 30k service and BMW NZ subsequently sent the part and it was then repaired at no charge even though slightly out of warranty. Well done BMW and Motomart.