Go back to you original description of the problem as synchronous to crank movement.

This points to a crank/chainring/BB/pedal cause, or somthing power or chain tension related. Since it's SS start by verifying good chainline, and that the chain isn't rubbing down the side of the chainring. Poor chainline, combined with a dry chain and/or nicked chainring teeth will cause the type of sound you describe.

Also, modern external and cartridge BBs are prone to noise under max pedal load. It could also be the pedal threads, remove the pedals clean the threads and mating faces and replace, using a pedal washer sometimes solves pedal thread click

Lastly it could be something related to the chain load on the rear hub. Things that sound like BB noise are a broken axle, loose locknut, and flex of the axle at the dropout.