The message that you are getting is due an " ACR Mismatch " between the 2 applications that you are working on .
So when you receive the mis-match warning in Lightroom, simply use the " Render using Lightroom " option. This uses Lightroom's ACR engine to render the file , and then passes the file to Photoshop for Editing.
The only real consequence of doing this is that the rendered file (Tiff or PSD) is created by Lightroom (and appears in Lightroom) before it's passed to PS for editing. If you edit and save in PS, no difference to a LR6.3>CS6 workflow, but if you cancel out of the editing in PS you are now left with a Tiff/PSD in LR which you probably don't want and so have to delete. Other than that, the workflow works fine.
Thanks for the information.
I found out the reason for the mis-match: Adobe ( You guys), have stopped providing updates to Photoshop CS6's camera raw. What a crappy idea. I read that CS6 is the last stand-alone version as well.
Not happy with either.
I do not like using the CC version as I am just an occasional user of Photoshop.
I will do as you suggested, which works, but will be looking for alternatives to photoshop for those occasional uses.
With all the issues you guys had with Lightroom 6.2 I don't know that I will care to use your products much longer.