Customize How Records Get Approved with Approvals

After reading all the posts and various error messages I went and made some corrections to my approval process.  
But I still get the following error:

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Process failed. First exception on row 0; first error: REQUIRED_FIELD_MISSING, missing required field: [nextApproverIds]: [nextApproverIds]

I am not sure what it means by missing required field: [nextApproverIds] does anyone have an idea on how to fix this or is this another known issue with this module?

Thanks

The trailhead: Importing Data - Challenge keeps failing - see error message

There was an unhandled exception. Please reference ID: KMOEAQSC. Error: Faraday::ClientError. Message: INVALID_FIELD: SELECT Name, Id from Contact where Email LIKE '%example.com' ^ ERROR at Row:1:Column:36 encrypted field 'Email' cannot be filtered in a query call

I have disabled encryption and un-encrypted the "email" fields.  

How can I get around this error?  Or should I just spin up a new Dev Org?

I am not able to complete the che challenge "Set Up and Manage Shield Platform Encryption". Everytime it shows "The Case Description field does not appear to be encrypted. Make sure you have records with data in this field." Although I encrypted the Case description filed. Anyone have any idea how to get rid of it. Please help me. I am stucked in this step for two days.