@Srinidhi maiya , From your description, it seems the URL with mcas configured is not working in WIP. If there's any misunderstanding, feel free to let us know.
Research and find a customer who adds the MCAS Proxied URLs in both Protected Domains and cloud resrouce is working well. We sugges to add the URLS in the both locations:
http://procloudguru.com/overcoming-wip-limitations-on-byod-w10-with-conditional-access-app-control-policies/
Note: Non-microsoft link, just for the reference.
After that sync on the device and see if it is working.
However, if the issue stills perists, please follow the steps in the following link to troubleshoot:
https://www.anoopcnair.com/troubleshooting-intune-wip-issues-checklist-1/
Note: Non-microsoft link, just for the reference.
Hope it can help.
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