If you've enabled Momentum on Safari mobile and are seeing a blank white page, you've come to the right place.
This blank screen displays when you have Private browsing enabled in Safari. To fix this, simply switch to normal browsing.
Switching to normal browsing in Safari mobile
To switch to normal browsing, tap the Tabs icon at the bottom right of Safari, tap Private at the bottom, and then select the Tabs option. Now when you open a + new tab, you should see Momentum.