Hi when I press the alt key and move the amount slider to sharpen image turns into a B|W version also if I do the same with detail slider image disappears and a grey panel appears, any solutions out there?
Your ALT key is working as designed- (try extreme adjustment to see effects at 1:1 view.)
With the [Amount] slider it is removing Colour from the image allowing a better impression of the sharpening with Luminance only.
With the [Detail] slider it is showing (very faint) how much the sharpening strengthens primarily edges.
With the [masking] slider it previews areas that will, or will not, be sharpened. White=sharpened, Black=Not sharpened.
For example- editing a fine (fashion women) portrait- you may want to sharpen eyes and hair but leave the skin areas un-touched, this is where the Alt+Masking will preview the areas where you are applying sharpening.
From a Lr 'Help' file-
Oh dear I now realise that thank you for your guidance
Sent from my iPhone