Power BI Gateway Refresh error for Sharepoint List

Hello, 

I am publishing a report in Power BI service on a Premium Capacity App Workspace. There are 3 different data sources. One is OData, one is Excel on OneDrive and the other one is from Sharepoint List. I have successfully set up the on-premise gateways for all three using my Windows credentials. I can refresh on the Power BI Desktop without any issues but when I try to refresh on Power BI Service I get the following error message: 

Data source error: {"error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","pbi.error":{"code":"DM_GWPipeline_Gateway_MashupDataAccessError","parameters":{},"details":[{"code":"DM_ErrorDetailNameCode_UnderlyingErrorCode","detail":{"type":1,"value":"-2147467259"}},{"code":"DM_ErrorDetailNameCode_UnderlyingErrorMessage","detail":{"type":1,"value":"'Implementation' isn't a valid SharePoint option. Valid options are:\r\nApiVersion"}},{"code":"DM_ErrorDetailNameCode_UnderlyingHResult","detail":{"type":1,"value":"-2147467259"}},{"code":"Microsoft.Data.Mashup.ValueError.Reason","detail":{"type":1,"value":"Expression.Error"}}],"exceptionCulprit":1}}} Table: Archived F&B Projects.
Cluster URI: WABI-US-EAST2-redirect.analysis.windows.net
Activity ID: 8217d136-eecf-4627-934e-f94dfd199acd
Request ID: 917f4255-64f7-5acb-0001-aa80ea344be5
Time: 2022-03-16 16:21:03Z

From above the only thing I could dig out is the Implementation not valid for Sharepoint. I've checked on Power Query editor and on the source step it is referring to Implementation=null, Apiversion=15. If I change the Implementation settings from 1.0 to 2.0 Beta I get an error message so I revert back to 1.0. I am just mentioning this in case it causes the issue.

Anyone knows why this happens and suggest any solution? 

Many thanks in advance,

George Aivazidis