Hi Abhishek,
having a similar problem like you. For us, we think it might be related with CSRF protection and maybe with the setup that our clients access the FES through x.mycompany.com whereas the server internally is configured as y.mycompany.com. So x.mycompany.com is a DNS alias pointing to y.mycompany.com.
We think there could be a problem when y.mycompany.com answers a CSRF Token request.
We could mitigate the problem by disabling CSRF check on node "/default_host/sap/opu/odata/ui2/interop" via ~CHECK_CSRF_TOKEN = 0. However, that would not be appropriate for production scenario.
Not sure though if this applies to you or if it even is our main problem.
Anyways, would love to hear if SAP came up with a solution to your problem.
Cheers
Jens