I made this model. After BooleanUnion it looks like this.
When I try to do FilletEdge, as more or less expected, because of these areas
the result looks like this. The resulting model has 12 holes in it.
I have had similar issues in the past with this small model.
In that case, after performing MergeAllFaces that took care of it.
I have tried MergeAllFaces on the new model, but that does not seem to work. What do I need to do to make FilletEdge work with my current model?