For both headphone jacks 1 and 2, the right ear is only like 5% the volume of the left. I've tried with multiple pairs of stereo headphones, same result. This is the case for all audio output including Logic and the Mac audio out (like Spotify).
I can't seem to find any pan-related settings, but given it's multiple headphones, both headphone jacks, and multiple apps, seems that maybe some setting is bunked?