WordPress automatic updates are done by WordPress, not iControlWP. This means it's dependent on the WordPress cron and its timings compared with the timings of plugin update releases.
So the first thing that needs to happen is WordPress needs to detect an update - WordPress does this once or twice a day. Then, the WordPress automatic upgrade cron needs to run, which is done twice a day. So these two things need to first happen (in that order) before a plugin is automatically updated by WordPress.
Furthermore.... the WordPress cron isn't a "real" scheduling system - it's only run when someone visits the site.
So there are 4 timing factors determining WordPress automatic updates after a plugin update is released:
- the timing of the plugin update release
- the timing of the updates detection "cron" (dependent on your visitors)
- the timing of the automatic updates system "cron" (dependent on your visitors)
- the timing of someone visiting your site to trigger these two processes.
All of these play a role together in automatically updating your plugin. You may need to wait up to 24hrs for WordPress to detect and automatically upgrade a plugin or theme.
For more information on WordPress automatic updates, read the blog article here.