Hi WN,

re:
> Hi, Michael.
> The fillet tool does not work with this geometry.
> Will there ever be a fix or always use a workaround?

Actually no there will never be a fix that covers every single type of possible geometric shape because geometry comes in infinite varieties so it isn't possible to test every kind of shape. That's one of the things that makes this a difficult area for software.

But usually there are not a lot of problems in curve filleting compared to solids filleting.

In this case here it's related to the specific "anti-tangent" shape you've made.

For this particular bug a quick workaround is to use Edit > Separate and then select 2 separate curves at a time and do Fillet, followed by Edit > Join. That will avoid the bug in the corner processing for this case which I've added to my list to investigate fixing.

- Michael