Fillets should always be the last operations. That means when one wants to add more features like holes/pads etc, one should add those to the object before the

Fillets should always be the last operations. That means when one wants to add more features like holes/pads etc, one should add those to the object before the fillets. Sometimes the fillet operation fails in odd ways though, usually when the number of edges changes. Then one should re-do that last operation, either by removing the Fillets and adding again. Or in 0.18 edit the Edges that the Fillet operation is using in the Property window.