I do not see a *.sldprt file attached, only an image?
I am not familiar with using SolidWorks as an image editor.
Have you tried with smaller radius? Then gradually increasing? What do you observe?
Have you tried a Face Fillet rather than Edge Fillet?
Make sure that all letters merge with the base properly. For that you can extrude them little more to make sure that they merge well. Finally try the fillet.