I am running Lightroom 5.7 (Camera Raw 8.7) in Windows 7. Lightroom will import smaller cr2 raws (typically 10-11 MB). When I attempt to import larger cr2 raws (typically 20MB) I always get the message: "The files are not recognized by the raw format support in Lightroom." Help>Check For Updates shows "Your software is up to date. No updates are available at this time." Support shows that Canon G7X Mark II raws are supported by Lightroom over v5.5 and Camera Raw over v8.7.
Any suggestions on how to fix this?
For that camera you need LR 6.6, CC 20015.6 or above with camera raw 9.6 or above. The only way to get the newer version of camera RAW is to upgrade LR.
Or you can use the free Adobe DNG converter to convert those CR2 files into DNG files. Then LR 5.7.1 will be able to import them.
According to the list of supported cameras published by Adobe, you need Lightroom 6 .6 or camera raw 9.6 to have support for that camera model. It isn't the size of the files that is giving you the problem. You need a newer version of Lightroom or else you will have to use the DNG converter.