So when using Type 3 for your disk type the system expects the Read Write and the Read Only disks to be open at the same time. If you close the Read Write before the Read Only then consolidation doesn’t work correctly and you get an error message. Also if the Read Write version of the disk can’t acquire an exclusive lock, for any reason, then it thinks it is in use and creates the Read Only. If storage is having an issues creating that lock, you get Read Only.