Hi Team,
Right after this post, I tried to monitor the network log by inspecting an element from the UI Browser and found that the UI API is taking different parameters.
{"access_control_list":[{"user_name":"xxxxxxx@xxxxxx.com","permission_level":"IS_OWNER"},{"group_name":"data-scientists-dev","permission_level":"CAN_MANAGE"}]}
Then I used the same body param and was able to set the permission.
If you guys have any other inputs please do share.
Amit Prajapati