Howdy.

Why am I losing an inch off this part when flattening?

The larger version flattens at 52.681" but the smaller flattens to 51.681" despite being lofted from the same sketch. 

It mentioned losing the cut feature when flattening, but I didn't realize it was because one inch of it was missing. I have another part lofted from the same sketch that flattens correctly.

Edit: Using SW 2018 SP5.0