Why does FILLETEDGE fail on some 3D solid edges?

[indiancad]

Have you ever tried using FILLETEDGE on a 3D solid, only to find that the command fails or produces an unexpected result?

One thing I check first is the fillet radius. If the radius is too large for the available space, AutoCAD may not be able to create the transition.

I also inspect nearby edges and faces for small or complicated geometry that could interfere with the operation.

When a fillet fails, I usually try a smaller radius first. If the model has several details, applying larger fillets before adding smaller features can also make the process easier.

When FILLETEDGE fails, what do you normally check first: the radius, the edge selection, or the surrounding geometry?