if ya wonna reverse 1 bar. i would in logic hilight that block in the audio channel. then open it in logics audio editor and simply reverse it. just that bar. theres loads of ways to get round it just gotta doit the way it works for you. maybe bounce down just 1 bar of your tune then reopen it into a audio channel then reverse it with the built in audio editor. even recycle it after and open it back into a audio channel.