Large radius objects are tough. The angle is severe at the lower layers causing the printer paths to be far apart and they don't want to bond.
I think I'm in agreement with @Longtoke regarding moving the ball up off the build plate (2mm sounds good) and letting the underside be all support structure. I know it won't leave a great finish, but it should print. Another thing to try would be Adaptive Layers.
No go on the picture sadly Zorg, but I'll ask a few questions that may assist us in helping you.
Is the model too big for the build area ? - if it's even slightly outside, it can cause what you might describe as greying of the model.
Is the progress bar popping up while slicing ? and is it completing the slicing process completely before you then try to preview the model ?
You said you're having it happen on all slices now ? have you tried to slice something that you've successfully sliced previously without issues ?
If it's none of those, we may need to dig deeper, and I would recommend updating Cura too, after backing up all your profiles etc, then try the new version of Cura with the default profiles first, then the new version using your imported profiles.
One of those / more info and we should be able to figure it out 😉