Thanks for reporting this issue! It sounds like you may have found another bug in the firmware.
If I understand you correctly it happened on your friends 1DX, her 1.4xIII, but you used your 180mm Macro, and not hers?
It would be great if others can test this with the same set-up above as you did, just in case something is wrong with your Canon 180mm Macro lens. I understand it works on your 5DIII, but you know how these bugs work.
Can others please test this combination and report it back here and/or to Canon?