I think your camera needs Lightroom v4.3 to allow imports. Cameras supported by Adobe Camera Raw
This would be a free update from v4.
Other options are-
1. upgrade Lightroom to v6.4 (buy)
2. Convert the CR2 files to DNG with the free Adobe DNG Converter, then import.
when I check for updates, it says I'm up to date.
Seems like the update mechanism is not working properly.
The latest version of Lightroom 4 is 4.4.1.
Download and install it from Adobe - Lightroom : For Macintosh : Adobe Photoshop Lightroom 4.4.1
You should then be able to open the Raw files from the 6D.
Thanks, John. It seems you were correct about the updater, I think it was v4.1, not 4.4, but still getting the same message after the update download.
I tried the DNG converter and it says the "folder doesn't contain any supported camera raw files. Not sure what to make of that message, since the folder is full of .CR2 files.
Would PhotoMechanic have some sort of import/ export option?
I think it was v4.1, not 4.4, but still getting the same message after the update download.
Check that you are definitely running 4.4.1.
In Lightroom, click Lightroom (in the top menu bar) About Lightroom. Which version is shown?