Earlier this year Facebook introduced some changes to their API which broke autopost features in many plugins include Jetpack. Many users were up in arms against these changes as they could no longer post to their personal Facebook profiles or Facebook groups.
However, there is still a solution that works perfectly fine.
Download the SNAP Social Networks Auto Poster plugin and subscribe to the premium API, which you will then use to post to Facebook instead of FB’s own API.
I use it on all my sites on a daily basis so I can vouch for it working perfectly well as of September 2018, and I don’t see it stopping anytime soon.