DMN Editor: none example of importing models in kie-dmn-core opens in editor

the editor keeps "Loading" with the circle.

Any importing model in: https://github.com/kiegroup/drools/tree/master/kie-dmn/kie-dmn-core/src/test/resources/org/kie/dmn/core/imports

I tried to identify manually by:

• adding the optional locationURI
• removing any un-necessary attributes (redundant triso: and drools: attributes)
  but none solved.

Please advise.