The logic is simple: 

If Pope says no dogma, doctrines, disciplines or canons were changed, then we are charitably obliged to first look for other causes than heresy, when Irregular Couples du jour receive communion, anew, having been away from the Lord's table.

One way of interpreting one dimension of Amoris is that it didn't reformulate, for example, Canons 916 & 915, and related, but exhorted RENEWed emphasis on their original legislative intent! 

Amoris was thus a ressourcement of legislative, pastoral intent that can foster an aggiornamento of mercy & healing, because, for example, 916 already had canonical epikeia available, e.g. internal forum solutions, and 915 already had practically insurmountable evidentiary & prudential hurdles, e.g. occult-manifest continuum.

Under 916, its the de facto in/validity that will indicate adultery or not, not the juridical recognition of same or its lack. Under 915, "manifest" is a rigorously defined legal term. Rigorists, take note!