stbyrud:
AFAIK the logic is inhibited on the ground after a certain software version - noticed that the ANP was exceeding 10 NM while the IRS were aligning the other day and the aircraft didnt say a thing. On another ship (with older software) it immediately complained (UNABLE RNP) when the IRSs were turned on for alignment...
Perhaps the newer software was RNP AR compliant, which has far more demanding performance requirements than "plain vanilla" RNP.