If you are loading a production IODF with an associated MCF, HCM downloads the MCF and opens the master configuration. Since the master configuration associated with a production IODF is always a work configuration file, you now have an in-sync, up-to-date configuration, but you may not be ready to continue to work with it.
When loading a production IODF, HCM always creates a work configuration file first. Therefore, hcm(z) is offered as the default file type in the Choose Local File dialog. This behavior is not new with the MCF functionality. The created work configuration is immediately usable only for viewing or for physical-only updates.
When loading an MCF-enabled production IODF, HCM offers to additionally create a production configuration file. Creating an associated production configuration file is recommended, but not mandatory (for example, for just viewing an up-to-date state of the master configuration).
Even if you do let HCM create the production configuration, it still opens the downloaded work configuration file first. This is to keep the behavior consistent with older releases of HCM. At this point, you cannot apply logical changes because the associated production IODF cannot be changed. Also, the menu choice File ---> Make Work is disabled, because HCM enables it only for production configuration files. If you want to just view an up-to-date state of the master configuration (or if you want to apply purely physical changes), the opened work configuration is sufficient for that purpose.
Often however, you now want to apply (physical and logical) changes to a new pair [work IODF, work configuration file]. In order to be able to create such a pair, you first have to close the work configuration and open the production configuration (which you previously allowed HCM to create during loading of the MCF-enabled production IODF). Here, the menu choice File ---> Make Work is enabled and allows you to create the new work configuration pair.