In Library mode, any attempt to display a 50 Mpx RAW image in any 1:n magnification results in a grey box. Image appears only in FILL and FIT views. This renders the library mode useless for culling ultra-high-resolution images for fine focus or motion blurr so I'm basically forced to use a non-Adobe product for that simple function.
I've tested this with images shot on Canon 7D, 5D mkII, and 5D Sr. Images from the 5D Sr are the only one's that have a problem and it's only since the new Classic CC 7.0 release that this has come up.
PLEASE GIVE US BACK THE OLD VERSION OF Lightroom CC. It may have been slow but at least it worked.