Are you talking about auto tone adjustments?
Which version of LR are you using?
When you say it is no longer visible, when exactly do you see it as not visible?
Perhaps you have Caps Lock on? That sets auto advance on. Just turn Caps Lock off.
i tried this before. The effect was, that it invertet the behavior für P or X-Selection → means, there was no automatic forward, but i clouldn't rate Stars, because Caps Lock was on.
BUT i just testet it one more time to answering your question, and now the menu-option was available again.
Maybe because trying some things like Caps Lock or Shift-Key before and closed/restartet Lightroom in between, which is startet therefore so many times...
Don't know, but i'm very lucky to have back the normal behavior now.