The INC/DEC instructions block the control signal that updates the carry flag. This happens in the carry flag circuit.(See footnote 10.) For LOOP, the microcod

The INC/DEC instructions block the control signal that updates the carry flag. This happens in the carry flag circuit.(See footnote 10.) For LOOP, the microcode doesn't have the F bit set, so the flags aren't updated from the ALU. Same with NOT.