This is seriously difficult to explain as it seems to be a constantly changing bug. Essentially what is happening is that most of the built in guitars and bass sounds are only coming out of the left side; not all of them but most of them. This is through my audio interface Behringer U-Phoria UMC22. I also have a brand new Focusrite Scarlett Solo interface which, when I switch over to that, a few more of the guitars work fine but most of them are still only coming through one side - this time it's the right side. A few minutes ago I recorded a piece using the guitar sound 'UK Vibration', in 'Crunch guitar' and it was working fine on both sides. I then changed the sound of that channel to 'Big Spinner' (also in the Crunch effects) and it works loudly on the left side only. However, I then duplicated that track to record again with the same sound, and now it's really quiet, still only on the left side (wtf???). I've tried everything to resolve this, even to the point of uninstalling Logic and reinstalling it. I have two different audio interfaces, one of them brand new, so I can't figure out why this 'bug' is acting differently with both of them. This has only started happening recently and I've never experienced it before, having used Logic Pro X for the past 5 years at home and at college. It just seems to me that Logic has a mind of its own, and does whatever it feels like, and I have no idea how to fix this as there's nothing online about it whatsoever. Please help!