Check the model view options saved with these views. There is an option to show fills solid.
An aside: I when I want the background of an object or fill to hide what is behind it, I prefer to use the masking fill, white as it gives visual feedback that a mask is set to show. In the USA library the masking pen is 91. In the other versions it was changed, I think it's pen 28.
My screen background is similar to cream colored trace so the white shows clearly. If you have a white background, there is a a Work Environment setting User Preference Schemes> More Options> Automatic Pen Color Visibility Adjustment for Model Views which will gray one of the whites so the difference is still noticeable. It has no affect on printing.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"