I have the same problem. Scheduled posts aren’t posted to Social Media (Facebook) and I see nothing in the log. If I manually publish a post it does work and I see the status of the Social Media accounts in the log.
I’m using NextScripts: Social Networks Auto-Poster 4.0.8 and NextScripts: SNAP Pro Upgrade Helper 1.4.4.
Disabling WP-Cron and setting up my own cronjob in DirectAdmin doesn’t work either, I see my own cronjob does run OK in the log though. The scheduled post is published but SNAP plugin doesn’t do a thing.