Glas s, stainless steel , anything with a shine is rendering black!
What do I do?
It may be that you got unlucky and picked out "New" items that have rendering glitches. Or it may be a bug on the site - in which case other people will come along and post they are having the same problem.
Things to check - do you have windows/enough windows in your design? (note that glazed doors do not have the illuminating effect of windows)
Try taking out a few of the items and adding something similar and re render
If that doesn't solve it and noone else is reporting an issue then suggest using the "feedback" facility - bottom left in the 3d planner to ask the technical team for input.