The issue is that the DMC appears to be stuck in "Standalone" mode. When they go into the DMC Overview page, it states that it's in "Standalone Mode". When they first enter the DMC "General Settings" page, it states that it's in "Standalone Mode". After we change the mode to "Distributed", it shows all of the instances' settings from the previous editing.
If then click "Apply Changes" and appears to do nothing. When we leave the screen – and allow this to occur without saving my changes, which reinforces the appearance that "Apply Changes" is not working – and return to the General Settings page, it says it's in "Standalone" mode.