Can't Disenchant Item with Grindstone

I have a pair of Netherite boots with the Silence Armor Trim, Redstone Material, and Protection IV, Feather Falling IV, Depth Strider III, Unbreaking III, and Mending I. When I place them in the upper slot of a Grindstone, a red X appears over the arrow pointing to the Disenchanted slot and I cannot disenchant the boots.