Don't take my word for it but i'm gonna give it a try, i have an idea why ..

Moon Scrolls are the currency we get from doing our Daily Missions and Activities, so it includes Arena, Ranked Battle, Team Instances, Strong Approaching and Space-Time while Sun Scrolls are the currency we get from participating in Timed-Events such as Nine Tails Invasion, Rescue the Jinchuriki, Cat Quiz, FIghting Matsuri and Sage World Battlefields .. So it is logical if we will only get Moon Scrolls and not the Sun Scrolls since the currency we have or the points we have in 4.0 shops are from those Daily Missions and Activities .. And for the Survival Trial, it is remained as it is since the points from Survival Trial is now used for the Ninja Collection System, where we can buy and get Ninja Fragments ..

Yupz, you c*so find a list of what features can get you Sun or Moon Scrolls by pressing on the "+" *on next to their respective scrolls.

Sun Scrolls:

Moon Scrolls:

Unlike the Sun Scrolls, the Moon Scrolls are associated with features that had a currency and shop, so those currency were converted into Moon Scrolls, while any excess currency was converted into Strange Stones.

~Jib