Please help me find the cause of the clicking sound while pedaling. The drivetrain is GRX600 2×11. The chain is waxed. More in post.

There's a distinctive clicking sound while pedaling that seems to originate from the drivetrain. When I spin the pedals without sitting on the bike, the sound is not there.

So far I have tried the following non successfully:
1. Unclip either shoe and pedal with just one to see if the sound comes from there.
2. Stand up from saddle but the sound is still there.
3. Turn the clutch off but nothing noticeable happens.
4. Changing the gears rear or front also does nothing…
5. Turning the rear derailleurs adjustment bolt does nothing regarding the sound.

So yeah… I'm quite lost now and starting to think if there's a problem with my waxed chain. The chain has only ridden 25km from last waxing. The drivetrain has been used less than 1000km.

My friend has a new GRX600 2×11 that's completely silent. What I noticed is that my clutch button is operated with much more friction than my friend's. Maybe that's a lead..

Thanks for any help.