Scheduled Refresh Failed - missing credentials - Data source credentials greyed out

I was able to figure out how I had fixed this issue using morgangrobin's answer. I had previously copied the excel data and pasted it into PowerBI Desktop (thereby, "entering" it in). This does the trick. However, if you're data sheet is live (i.e. it gets updated regularly, particularly by others) than I would recommend morgangrobin's solution as a more general option. 

The data source is a Kusto cluster. To get the data I clicked Advanced Editor and entered the below query. 

let KustoQuery = 
let Source = Json.Document(Web.Contents("https://********.kusto.windows.net:443/v1/rest/query?db=artreporting&csl=.show version",[Query=[#"csl"="let *** = '***'; let *** = '***'; TableName | project meterId = resourceId, subscriptionId = reportingId, units, usageTime | where usageTime > ago(1d) | where meterId in (***,***) | extend usageDate = strcat(datepart(""Year"", usageTime),""-"",datepart(""Month"", usageTime),""-"",datepart(""Day"",usageTime)) | summarize sum(units) by subscriptionId, usageDate | join kind=inner ( cluster('***.kusto.windows.net').database('***').CustomerSubscriptions | extend subType = iff(OfferType == ""Internal"", ""Internal"", ""External"") | project subscriptionId=tolower(tostring(SubscriptionGuid)), TPID, TPName=CustomerName ) on subscriptionId | project subscriptionId, TPName, sum_units, usageDate ",#"x-ms-app"="PowerQuery",#"properties"="{""Options"":{""servertimeout"":""00:04:00""},""Parameters"":{},""PrincipalIdentity"":null,""ClientRequestId"":null,""SecurityToken"":null,""AuthorizationScheme"":null,""RequestHostName"":null,""LocalClusterName"":null,""Application"":null,""User"":null}"], Timeout=#duration(0,0,4,0)])),
TypeMap = #table(
{ "DataType", "Type" },
{
{ "Double", Double.Type },
{ "Int64", Int64.Type },
{ "Int32", Int32.Type },
{ "Int16", Int16.Type },
{ "UInt64", Number.Type },
{ "UInt32", Number.Type },
{ "UInt16", Number.Type },
{ "Byte", Byte.Type },
{ "Single", Single.Type },
{ "Decimal", Decimal.Type },
{ "TimeSpan", Duration.Type },
{ "DateTime", DateTimeZone.Type },
{ "String", Text.Type },
{ "Boolean", Logical.Type },
{ "SByte", Logical.Type },
{ "Guid", Text.Type }
}),
Exception = Source[Exceptions]?{0}?,
Result = if (Exception <> null) then 
error Exception
else 
let 
DataTable = Source[Tables]{0},
Columns = Table.FromRecords(DataTable[Columns]),
ColumnsWithType = Table.Join(Columns, {"DataType"}, TypeMap , {"DataType"}),
TableRows = Table.FromRows(DataTable[Rows], Columns[ColumnName]),
TypedTable = Table.TransformColumnTypes(TableRows, Table.ToList(ColumnsWithType, (c) => { c{0}, c{3} }))
in
TypedTable
in
Result,
#"Changed Type" = Table.TransformColumnTypes(KustoQuery,{{"usageDate", type datetime}}),
#"Sorted Rows" = Table.Sort(#"Changed Type",{{"usageDate", Order.Ascending}}),
#"Renamed Columns" = Table.RenameColumns(#"Sorted Rows",{{"sum_units", "Number of Tests"}}),
#"Changed Type1" = Table.TransformColumnTypes(#"Renamed Columns",{{"usageDate", type date}})
in
#"Changed Type1"

I'm not sure what connection mode or advanced operation in query tables is. 

I can't edit schedule refresh settings because it's greyed out

I'm using an organizational account to access the Kusto cluster. 

Refresh history is in the image below

Same, any chance were you able to figure it out?