I was previously using Lightroom 5 and I recently purchased a Canon 6d Mark ii. I researched and found that Lightroom 5 did not support files from that camera body without a dng conversion. I was due to upgrade anyway, so I purchased Lightroom 6 (perpetual) and have updated the program to 6.3. However, I'm still not able to view a preview OR import images to Lightroom from my SD card.
I'm beyond frustrated. Any help would be greatly appreciated.
According to the published list of supported cameras, that model began to be supported in Lightroom 6 .12. Are you receiving any error messages? Are you certain you have installed Lightroom 6 .13? What is the exact version installed on your computer?
Added later: I just read your question again. You indicated that you had updated to 6.3. That isn't recent enough. The most recent update is 6.13. The update that you have installed isn't new enough to support your camera. Get the latest update, and you should be good to go.
As Jim says to clarify .3 is update three .13 is update thirteen.
You can look at the link below for the history of Lightroom development.