I'm in the last challenge and get this message: 
Challenge Not yet complete... here's what's wrong: 
Could not find the setup of your My Domain in your org. Ensure that you have properly set the Background Color. Make sure that you've received an email from Salesforce notifying you that your domain is ready for testing before running this challenge.
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Customize the Lightning user interface
Make all Lightning UI modifications as outlined in the requirements document. Change the background color in your My Domain settings for authentication configuration before submitting this challenge.
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What should I do?
 

I'm in the last challenge and get this message: 
Challenge Not yet complete... here's what's wrong: 
Could not find the setup of your My Domain in your org. Ensure that you have properly set the Background Color. Make sure that you've received an email from Salesforce notifying you that your domain is ready for testing before running this challenge.
------------------
Customize the Lightning user interface
Make all Lightning UI modifications as outlined in the requirements document. Change the background color in your My Domain settings for authentication configuration before submitting this challenge.
--------
What should I do?
 

 "Locked filter" related error during check challenge of Report dashboards super badge. Attached screenshot please replay.