Okay, after a bit more tinkering, I think i know what's happening,
but i've no idea why or how to correct it.

Application.WorksheetFunction.Max or Application.WorksheetFunction.
Min seem to be evaluating the entire named  range but are returning
the value of the first cell in the range  not the value of the cell
that corresponds to the actual max  or min. Don't know if this sheds
any light on what's happening.