Hi bisenberger, I've attached an edited version that has that edge removed:



The key to getting rid of that edge is forming this curve as one single segment (used your original segments and then did a Rebuild on it to fuse them into one long single piece):




The attached 3DM file will now fillet ok in these areas here:






However, you've also got another type of thing that is also problematic for filleting which looks like a surface which is very close to being tangent to surrounding ones but possibly off by just a few degrees:



It's going to be difficult for the filleter to deal with things that cross over that edge - for filleting it would probably be better if that was actually a sharp edge instead of trying to build a smooth feature there - if it was sharp then you would include it along with the other edges during the filleting to smooth it out. A lot of times it can actually make things easier on the filleter if you let it smooth out some edges like this rather than trying to build a smooth surface manually there - when the filleter would smooth it out it can actually make it easier for it to form corner patches in the junctures where fillets collide into one another. In this situation it will be more difficult for the filleter to form the corner junctions.

- Michael