Case1:-
If somewhere around, after 15mos of your FP1, your FP2 was generated, then this falls into a case wherein your case is not yet assigned to an officer[at that point of time atleast], and hence the automatic FP generated a FP2.
For most of those who fall into this category, online message after FP2 would NOT be reflected...!
These need to be assigned to officer, and he can either approve, send RFE or Transfer based on the individual case.
I AM IN THIS I GUESS...
Case2:-
If FP2 is generated more than 16mos or so after FP1, then it looks more likely that these cases had been assigned to the officer[at the point of time FP2 was issued by the officer], and mostly for these cases, online would reflect FP2 and either an RFE would have preceded the FP2 , [or RFE can be issued later, if clarification is needed] and once FP2 reaches, when the officer takes this case, it would get approved...!!
Just my observation following this board postings..
Hope our cases get approved soon