Fillet edge deletes surface

7-test-2.3dm (163.0 KB)
Just loaded up the latest WIP for first time to check its fillet edge command (yes I know it isn’t perfect). When I fillet (blend) edge, 0.4 rolling ball, the surfaces of the cylinder gets deleted. This also happened on a previous test I did. Is it me missing something or is there a problem here?

if you use the preview feature of the fillet command you may be able to see where the problem is. It’s likely a smaller fillet may work-