I just solved the problem. It was something very strange that I had to do two years ago to make the crop tool work. I forgot all about it since it has to be added manually in the Height and Width boxes and is not documented anywhere.

I had it set to 850 x 1000 at 300 Resolution. Pixelinches was selected.

PS tried to crop at 850 x 1000 inches and not pixels. This ate up all of 40 GB and it asked for more. pix had to be added manually in the Width and Height boxes to get a reasonable file size. The question I am asking myself is: why am I not able to select pixels in the first place?