If the white areas represent places where there is no RIOS activity_portfolio data, then those places are not being chosen by RIOS to have activities done on them. It only has a limited amount of money to spend, so unless you give it a large enough budget to cover the whole area in activities, not all of the pixels will have activities assigned. Usually people use RIOS to choose only the best places to do an activity, so they can prioritize where to work first.
~ Stacie