The convention in Flying Blue has always been that any fare classes not shown in the earning table are excluded from earning. They show all the fare classes that earn - anything else, by convention, does not earn. A fare class does not have to be explicitly listed amongst the non-earning fare classes, meaning that where they list non-earning fare classes, this list may not be exhaustive.
A is Premium Economy on Longhaul; indeed, Alitalia no longer has a domestic "A" class, but this does not invalidate FB's notation that domestic "A" doesn't earn.