What is this mysterious ticking noise?

As I pedal, I’m getting a clicking sound from the rear drive chain area. It’s a distinctly different sound from the rear wheel free hub. It happens on all four gears.
I am using silca secret immersion wax and super secret drip wax – which has worked fine (and silently) on my other bikes – Road/Gravel Shimano/Sram. So I’m a bit flummoxed as to what is causing it; and whether a component somewhere is being worn away.

Any advice would be greatly appreciated! Cheers