I have a part with base that is a planar edge, shown below in blue, parallel to the top plane.  I'm trying to figure out how to fillet that edge so that the base is still flat (i.e., the bottom of the fillet is planar parallel to the top plane).  A constant radius fillet results in an uneven base that is not flat.  I also tried a full-round fillet as suggested in ​ , but the operation fails.  It fails even when I tried segmenting the edge and adjacent faces. The edge forming the flat base that I'd like to fillet is in blue here:

Ideally, I'd like the fillet to continue all the way around to include the edges that aren't on the flat bottom as in:

I attached the SolidWorks 2015 part file.

Thanks for any suggestions!