Y Axis UoM on Resource Profile

 I may as well throw this question out here.   

We have defined a material resource, given it a UOM of LF (linear ft).  We pull up the Resource usage profile, and before we assign the resource to any activities, the Y axis correctly shows LF as the units.  Great.  Now, we actually assign the resource to a task (to which no other resource has been assigned).  Before our very eyes, the UOM in the Resource profile changes from LF to h (hours).   Anyone run into anything similar?  I've tried and tried, but I can't get the UOM to be anything but hours once the resource is assigned to activities.  Interestingly,