Refresh Issue in Power BI Service

Hello,
 
I have a PBI report where in Azure Cost Management (ACM) and Web are the data sources in it. The ACM connector is configured with OAuth and Web Connector calls a Microservice API with OAuth type of authentication. And the Microservice API has a relative path with encoded URL in it. Now this power query is running fine and refresh is completing successfully in Power BI Desktop. But when I publish this report to PBI service and create a template app from it, the refreshes are failing with random errors in the installed template app.
Following are the details of how our power query looks with ACM an Web connector;
let
 
Source = AzureCostManagement.Tables(#"AgreementType", EnrollmentIDorBillingAccountID , 1, []),
condition = Source{[Key="balancesummary"]}[Data],
#"Added Custom" = Table.AddColumn(condition, "Approved", each if Text.Contains([name], EnrollmentIDorBillingAccountID) then "Approved" else "Stop"),

Custom1 = if List.Max(Table.Column(#"Added Custom","Approved")) = "Approved" then EnrollmentIDorBillingAccountID else "0" meta [IsParameterQuery=true, Type="Any", IsParameterQueryRequired=true],
 
FilePath = "abc%2FDataTable1",
PathEncode = Uri.EscapeDataString(FilePath) ,
RelPath = Custom1 & "/" & FilePath,

Custom2 = Csv.Document(Web.Contents("https://*******/***", [RelativePath=RelPath]),[Delimiter=",", Columns=12, Encoding=1252, QuoteStyle=QuoteStyle.None]),
 
in Custom2
 
 
This report is created as a template app and installed . After installation customer clicks on "Connect your data" option. Then template app will provide data source configuration screens. First screen for ACM configuration and the second for Web. Here even though I am giving the correct valid credentials, the refresh is failing with the reason " data source credentials are invalid". Then I am re-configuring the data sources and going for a manual refresh, but then it is again failing with the same error with ACM. Once I reconfigure the data source credentials and go for a manual refresh then it is failing with the same error with Web connection now. I couldn't identify what is actually contributing to this irregular and random refresh failures (once with ACM and once with Web) and sometimes surprisingly the refreshes are successfully completing.
 
Can anybody help me in this to identify the connectivity issue and if there could be anything going wrong in the PBI backend which is not storing / missing/ overlapping the configured credentials with both the data sources?

Thanks
Lakshmi K