Hi Janani,   try this please

The issue was in the UI policy script. If you're using g_form.clearValue() to clear values in the script, please remove it from the UI policy and instead, use a Client Script to clear any variable values. This should resolve the problem.

Also, try using the Microsoft debugger to identify which variables are being cleared when you attempt to transfer the case from A to B.

Let me know if it solves your problem.

 if this does not work, then try to add the sn_hr_er_case_reader and sn_hr_er_case_writer roles to the assignment group from where you would want to initiate the transfer.  Just test with one assignment group first  in Dev.

 Hopefully this will help