I looked into your issue and found that make kibana does not produce dashboards which can be loaded. There is a Python script which unpacks dashboard data: https://github.com/elastic/beats/blob/master/libbeat/scripts/unpack_dashboards.py
You need to run this script in order to get loadable dashboards.
See how dashboards are packaged: https://github.com/elastic/beats/blob/master/dev-tools/mage/kibana.go#L31