Hi ,
I am doing the "Einstein Analytics and Discovery Insights Specialist" Challenge #3 and I am getting below error while checking the Challenge .
I am stuck since several days with this issue and as suggested in error I created new Developer Edition (DE)  org and checking Challenge still I am getting same issue in new and old org at Challenge #3 

Challenge Not yet complete... here's what's wrong:
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: MLDDDEXM