I keep running into weird limitations. Sometimes I can fillet an edge, sometimes I can't. Sometimes I can fillet any edge, but once I fillet one I can't fillet any other. With the "topological naming problem" that makes it hard to make changes to anything but the last step, it has been frustrating, but I hear it's improving all the time.
The fundamental issue here is that a fillet cannot wholly consume another edge.
It’s always worth doing your fillets last, but the other thing I would say is, where a fillet or chamfer is more than presentational as it were, build it into a sketch. Or cut it with a groove. Those operations are more reliable in OCC.
