Splits in the circuits are more common than you might imagine, and the Supreme Court doesn't always resolve them. A lot depends on how substantial the split is. Minor differences don't always get resolved.
In any event, this case isn't "ripe" for appeal to the Supreme Court yet. The Supremes rarely get involved until all lower court proceedings have been exhausted, and this case just got sent back for retrial on the issue of fair use. The process can be maddening for the individual litigants, but it makes sense for the legal system overall.