I agree with @osuire there is no reason why this should not work in Rhino for the reason being a surface modeler. It causes a lot of pain for many users, both beginners and advanced. Sure this is fixable in Rhino, but it takes quite a bit of knowledge, and when you decide the fillet needs to be 1mm bigger, you can do it all over.
You can see that in that model, there is no reason for it to fail either. The right lower corner fills correctly, while the lower left doesn’t. And that’s the most painful one to do manually. The other two are a quick fix, but since those surfaces are able to trim the corners correctly, there is no reason there it should fail either.
Furthermore, improvements to fillets are at the top of the list of user requests as long as I can remember.
Edit: the above refers to the other thread