If I recall there was nothing ontological about the actual Copenhagen group's interpretation. They aimed to develop a predictive theory and nothing more. One of their key insights was that ontology simply doesn't play a role anymore. This led quickly to the discovery of QM, while ~100 years of fussing over the "reality" of the wave function has led to nothing.

The "Copenhagen interpretation" as we understand it, in which some thing "collapses" when measured, trades under the same name but was invented later. As a result the original interpretations of Bohr/Heisenberg and their philosophy of science have somewhat exited the discussion, even though they had the only defensible epistemology -- the rest as you say is just ontology.