plugins - Cron task gets removed from the schedule

I have a plugin which I have deployed on four different websites. Part of that extension is a Cron job which triggers every hour.

On one of my deployments my job gets removed from the schedule. I used WP Control plugin to add it again (avoiding the reinstall of plugin). It worked for some time but then it was removed again.

I checked the logs and the removal of job from the schedule coincides with these other Cron jobs that were running at about that time wp_update_themes, wp_update_plugins, wp_version_check, woocommerce_cleanup_sessions

• Bellow is the list of the installed plugins:
• Advanced Custom Fields PRO
• Advanced Order Export For WooCommerce
• All In One SEO Pack
• Autoptimize
• Async JavaScript
• Complete Open Graph
• Custom Post Type UI
• Easy WP SMTP
• Disable Comments
• Gettext override translations
• Google Analytics Dashboard for WP (GADWP)
• Invisible reCaptcha
• iThemes Security
• WooCommerce
• WP Super Cache
• WP Crontrol

Is it possible that some these plugins is removing my Cron job from the scedule? What is causing this?

EDIT

This is how I add the Cron job in my init file of the plugin.

register_activation_hook(__FILE__, 'hourly_processing');

function hourly_processing() {
  if (!wp_next_scheduled('process-subscriptions-hourly')) {
    wp_schedule_event(time(), 'hourly', 'process-subscriptions-hourly');
  }
}


add_action('process-subscriptions-hourly', 'process_subscriptions_hourly');


    function process_subscriptions_hourly() {

//I do the processing here.
}