> I would consider working with density matrices, Lindblad equations, and more general Master equations to still be covered under the Copenhagen interpretation

> I would consider working with density matrices, Lindblad equations, and more general Master equations to still be covered under the Copenhagen interpretation Yes, but neither of those solved the problem of how to describe macroscopic measurements that result in definite outcome (eigenvalue of some operator). The collapse is still needed to continue the description after the measurement, only instead of psi function that should collapse, it is the density matrix that should collapse.