I have Lightroom 6.7 running on a mid-2012 MacBook Pro with OS X 10.12.2 (Sierra). I can import photos from a iPhone 5 - upon selecting import in LR and then select source the window shows iPhone 5 under devices. On trying to download from the Canon EOS Rebel T3i, selecting import in LR does not show any devices in the select source window. I have tried various combinations of USB connection, turning on T3i power, starting import and launching LR. I also tried using a different USB cable. None of these were successful. Also I am able to download photos from the T3i into the Apple Photo application on this computer. Also the photos are stored in the T3i in jpg format. What do I need to do to resolve this problem.
Sometimes, simply rebooting the computer can fix a problem like this.
As DJ points out, sometimes rebooting will fix the communication problem.
Ultimately, you will be happier using a card reader instead of directly connecting your camera. Card readers are faster in the file transfers, require no special drivers, are less error prone, and do not drain your camera battery.
DJ and ManiacJoe, Thanks. Rebooting worked. Bob