Has there been a change in policy concerning this? My memory is fuzzy. I'm pretty sure that entries got added when you right-clicked an underlined word and chose the correction off the list, so that when you typed the same thing it would be replaced by that correction. That doesn't happen anymore. And when I look at the autocorrect entries list to verify the correction doesn't get added.
Possibly it is a personal bug rather than an update.
It works for the dictionary (that is, when instead of choosing a correction you click "Add to dictionary"), i.e. the autocorrect exception entries, though.