Have you tried torquing down the crank with a torque wrench? Cranks need a lot of torque-around 300-400 in/lbs. If there isn't enough, that could be causing your issue. If nothing else, torquing your crank will rule out this issue. Also, rock the crank arms side to side with your hands. Is there any play in the bottom bracket?

I found a noise troubleshooting guide from park, maybe this can help too:

Troubleshooting a Noisy Drivetrain | Park Tool


Dave