A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
Hi BenjaminReed2,
Thank you for posting your query in our community.
Per your description, when a user try to refresh the power query in a SharePoint workbook, "microsoft.mashup.engine.interface.resource access forbiddenexception" error will pop up.
First, from the screenshot of Excel version you provided, this is not the latest version of Current Channel Excel, so we suggest that this user could update his Excel app to the latest version to see the result.
If the problem persists after updating, please let the user try the suggestions provided by Chitrahaas Nalla MSFT in this thread to see the result: Exception of type - Microsoft Community
Best regards,
Jazlyn