Nah, the cabin crew line has been there even on below MSN 1000 buses, however, it is or was an option, so not every airline ordered it.
Never happened to me, although it was installed on nearly all of ours. However, a simple call to the cabin manager would solve that, wouldnt it? Simply confirm it one more time that the cabin is secure. On landing that shouldn't be a problem as the button on the FAP becomes active only very late, i believe at RA alive or around that time on a standard ILS.