I think that you take your pics from too far away, with a general WIDE focus area for the light, and the white backgound here absorbs all the light,underexposing totally the front subject which is then black.
Select rather the light focus area on the camera only at the center point, narrow, and focus the center square (or circle) on the front subject, unless white, better dark or coloured, not the backgound, and your pictures will be perfect ! It will adjust the light of the subject correctly !!
