I recently got a Apple USB keyboard, and have been using it on my late 2013 MacBook Pro 13". It worked fine in either the left or right USB ports.
However, yesterday it stopped working in the left USB port and now it only works in the right USB port. I've tried it on other (non-Apple) computers and it works fine.
I've checked System Information, and it shows up when plugged into the right USB port but not when plugged into the left one. I've tried Safe Boot and also logging into the Safari-only guest account.
It isn't the USB port that isn't working as I can plug in my Nexus 7 and iPhone into the left USB port and they both still work.
What else could I try to get it working again? I'd like to use the keyboard in the left port since it fits better with my desk layout.