Can't zoom a LR Pano.dng file with a size of 927MB

Running the latest LR Classic CC 8.2 on a powerful Win10 desktop with 64GB of memory. Loupe View window turns black when attempting to zoom into a 927MB Pano.dng file. Image size is 28218 x 9823 pixels. It does not matter what zoom facor I select.....1:1 …..1:8, etc.

Anybody experiencing same issue?

Franz