By default, Merge Replication starts with a snapshot of the publication database and uses this to initialize subscribers. Afterwards, changes are incrementally tracked and replicated. The problem you are facing is that your publication database contains no data. You then use an empty snapshot to initialize your subscriber. And since by default article property Action if name is in use is set to Drop existing object and create a new one, you end up with no data at the subscriber.
What you need to do is backup and restore the database from the Express instance and restore it to the Standard instance. Then create your publication and subscription, generate a snapshot, and initialize your subscriber.