There is one use of sc_array_clear() in the test code [1] which really makes it look as if it is being used in a way that I think (again, I haven't single-stepped this code, only read it) leaks memory.
I agree on the pain of everything being macros, it's more pain than it's worth I think and will likely lead to code duplication (and more pain in debugging, probably).
I would even go so far as to think that this kind of single-file design, where each file is independent of the others, makes it harder and more annoying to implement more complicated data structures.
[1]: https://github.com/tezc/sc/blob/master/array/array_test.c#L3...