Audience Validation Failed - means when your token was decoded, it couldn't verify the "aud" from it. So make sure to check your token properly. use a jwt.io online service to verify your token. All should be good. I had the same issue, this was the ...
https://sap.sharepoint.com/teams/SAPAnalyticsCloud176/SitePages/Analytical-Insights-in-Joule.aspx?web=1Read the question - Q: Will Just Ask and Joule co-exist in SAP Analytics Cloud? you will find your answer @Cocquerel