Hi,
On a legendary item I tried to replace a starred / bold / critical affix.
It was the +15% all resistance.
It offered some subpar options so I selected the no change option.
The Occultist said that the item stayed +15%, but when checked in the inventory, it got reduced to +9,5%
Not a bug. Read the patch notes. Blizzard has already warned that enchanting will remove the greater affix, and that you cannot roll a greater affix onto an item.