Hello @Sweha ,
Thanks for reaching out.
I could think of two different potential issues in this scenario, one is "Invalid Token" and then second one is "CORS issue".
Invalid Token error, might have caused due to incorrect Kerberos constrained delegation for Application Proxy, read this article for Troubleshooting Kerberos constrained delegation
and for CORS issue, the following article is worth checking out as it speaks about common issues and resolution: https://learn.microsoft.com/en-us/azure/active-directory/manage-apps/application-proxy-understand-cors-issues
Hope this helps.
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