This is happening the last few weeks. Since it first started, one update actually fixed this, but now it returned again. There's something wrong with the wp_head section in the footer.php I suppose...
Admin bar disappears from time to time, when a new post is published and when new update to any plugin appears. Once the plugin is disabled everything works fine.
I'm not the only one having this problem but apparently I'm the first reporting it. It's a great plugin but it makes my website useless since it blocks all the plugins that load after it.