Hi Dave, also I tried importing your model into 2 other CAD programs (Rhino and ViaCAD) and both of them also have similar trouble trying to do a radius value of over 0.22 as well, most likely due to the same difficult situation in trying to connect up the different fillet pieces that I showed previously.

If a fillet radius of 0.2 is not large enough for you, I think you will need to use some other technique to build that particular part of the model instead of filleting, like maybe putting in a sweep surface there or something like that.

I've attached one result model that I made by trimming back some space and using Blend, it looks like this:



I started by drawing a curve in on the front planar surface, this is a lot easier in version 2 where you can use the View > CPlane tool to relocate the Top plan view to be looking straight down on that face:



Then I trimmed that front face with that curve:



Then I went into the right-side view and drew in a side cutting profile curve like this:



And then used that to trim those other surfaces:



Then I used Trim to cut up the edges of the planar piece so that they could be matched in pairs for blend like this:



- Michael