The problem is resolved. One of the processes was not set to "defaultPackage". Now I am able to see all the processes in the jbopm-console. But I would like to know how can I build a single process.
In Guvnor your assets are divided into namespaces (packages). You can validate a single asset, however when building you are building your entire package. You could divide your process assets per multiple packages the way it makes most sence to you.