As we were both responding on the other thread about the relationship calculator, I revisited my own FTM tree, for verification of my answer.
I promise you - cross my heart - I have made NO changes on my direct or collateral lines since our earlier exchange.
Tonight, FTM can once again see [I have many bad puns to hand, but I will restrain myself] the 3rd cousin relationship of my grandparents.
In the meantime (!) it has also found additional relationships! Previously, it found 6 - now it finds 9!