Annoying Internet diagnosis help needed.

When I put heavy backward resistance on my Omnium crankset there is a pretty loud single "pop" sound. When I then put pressure pedaling forward I get another single "pop" sound. I just regreased and retightened all the components and the sound still persists. The sound seems to be coming from the non-drive side BB/crank arm area.

Cog and locking are tight. No pedal or chain issues. No other noise while riding, everything feels smooth. I know there is not much that can be done via a forum, but is there anything else I should check or do? Should I completely disassemble and reassemble?