The reason you are not getting the value back is likely that the field sys_content (basically, "Content") is not marked as "retrievable". You can double-check this in Azure search portal.
If I'm not mistaken, this should be customizable. Check out this article - you'd need to hook into CreatingField.Before event, and if the field name is "sys_content" - change it's settings for retrievable to true. After this, you'd need to rebuild this index.