I've just made a few adjustments to some canon RAW images, including exposure, contrast, vignette, colour correction.white balance, but can't get a black image. All seems to be fine here. But, these are with images imported pre 10.5.3 upgrade, if that makes any difference.
Does you image go black while your adjusting it?, What adjustments are you doing? I'll see if I can get the same as you.
It really is very flakey, sometimes it works, other times with the same image it goes black. Sometimes you click auto levels and the levels histogram is blank.
I restarted Aperture and tried the same image, no problems. I have no idea what is going on and why it is inconsistent. Running 10.5.3 and just going to try the updated camera raw software update, though that shouldn't apply to my cameras.
Well, It was strange, after restarting Aperture the problems seemed to go away. I think I must have had some transient problem with a partial preview or something. I wound back to an earlier version of my Aperture Library using Time Machine and was able to recreate the problems I had again. Once again quitting Aperture and restarting fixed it.
I am hopeful that the problems are gone for good now.