Maybe I am not reading you correctly, vis versa. It should have gotten the 5FS designation, IMO. They must have questioned the 4th step.
There is a tiny part of the 6th step visible in the first quadrant above the space between the N & T of MONTICELLO. But you don't need 6 full steps for the designation, only 5 which this coin has, IMO.
There is a tiny area of weakness of the 4th step under the second pillar, but for decades NGC allowed that as long as it wasn't under the 3rd pillar and the 5th step was strong all the way across. Now, they are nitpicking to a ridiculous degree. At least it wasn't my submission this time and I got a full step coin for a fraction of the real price.