Thank you, George and Robin.
WooCommerce version is 2.5.5, PHP is 5.5.36.
Symbiostock -> Settings / system tab report in RED Exec Commands disabled. Diagnostic says “Warning: shell_exec() has been disabled for security reasons in /web/htdocs/…/home/wp-content/plugins/symbiostock-pro/admin-settings.php on line 1126”
Now I see some more media parsed from Symbiostok; maybe it needs some time to perform the task.
To solve cron management question, I’ve opened a ticket to my host provider.
Say you soon.