Q.Some of my oranges are split with a soft black spot and thin skin
The fruit looks dry.
Certified GKH Gardening Expert
It sounds like the tree has a problem or two. Read these two articles for solutions to the black spots and thin skins.
I'm reading that dry fruit is often due to a tree just being immature. Dry fruit may happen for the first harvest or two, and diminish as the tree grows strong and mature.
This article may also be helpful: