Since the 0.16.0 update, the any size slime can drop slime balls, and tiny magma cubes can drop magma cream. The wiki, which I believe is based on the java/pc version, states that the slime balls only drop from tiny slimes, and magma creams only drop from non-tiny magma cubes, which was the observed case in version 0.15.10.

I don't know if this is an intended change, but given the release notes do not list it as a feature, I'm assuming it is a bug.