This issue comes up a lot lately, since Poser 6.  When you load them, the sphere of influence will show up briefly, then disappear.  This is due to the new "feature" of Poser to be able to hide all deformers, show only currently selected, or show all deformers from the view menu.  The setting will override visibility of the sphere, because the default setting is "show only currently selected."  It is not helpful to "show all" because there are a million other spheres that you don't need to see, along with the magnets and bases.

So, included in the utility folder of UMM is a pz2 to turn individual magnet sets visibility (on or off)  Use those and you'll succeed.

-WTB