CRA has assessed CPP on my self-employment income despite a valid prior year election which has not been revoked. Is this a Turbotax software problem or a CRA problem?

Each year during the Turbotax interview process I confirm that I have made a prior year election not to contribute CPP on my self-employment income and each year it is ignored by CRA. I then have to file an online adjustment request to sort it out, which has always been accepted. But I wonder why CRA ignores the election.