Hello Bhaskar,

I'm able to create a new field in defect module and It can be visible when I create a defect. I think, It seems issue with the workflow customization code. Please see below details to resolve the issue.

Solution1:
Please check your customization code. If there is Workflow code overriding the value of the .IsVisible property of the new field, it will not show up; it must be set to TRUE in order for a field to be displayed. Also, remember Workflow code overrides customization done through the ALM Customization GUI which is why you must be careful when adding customization code. If you find some customization code needs to be removed in the future, please check all modules to make sure something like this does not happen.

Please refer below Eyeontesting article talks about the same.
http://eyeontesting.com/questions/12894/new-field-in-defect-form-does-not-display-in-any-o.html

Solution2:
You make sure not to hide the data in user groups and permissions. Please follow below steps to unhide the data in user groups and permissions.
1.In the Project Customization window, in the left pane, click Groups and Permissions. The Groups and Permissions page opens.
2.In the group list, choose the user group and make sure you can see the columns in the list in ''Data hiding'' tab.
3.Click the entity for which you want to unhide data. For example, click Defect. The pane at the right displays the filters currently set and the fields currently visible in the Defects module to the users of the selected group.

Solution3:
Site Parameter in ALM Admin for field visibility.
ENABLE_COLUMN_VISIBILITY_TRACKING: If this parameter is set to ''Y'' then column visibility changes made via workflow will affect trees/grids and column selection (will cause the relevant fields to be hidden). Default value: N

Customizing Defects Module Dialog boxes.
Step1: In Visible Fields, to set a field as a required field, select the check box next to it. For a required field, a value is mandatory. Its title is displayed in red in the Add Defect or Defect Details dialog box.

Step2: You can set the order in which fields are displayed for the selected user group by using the up and down arrows . You can also drag the field names up or down.

Step3: You can set the Add Defect and Defect Details dialog boxes to include one or more input pages. By default, all fields are displayed on one page. Use the up and down arrows to move fields to the appropriate page.

Please refer below link for more details.
https://admhelp.microfocus.com/alm/en/12.50/online_help/Content/Admin/cust_wkflw_defect_module_dbox.htm

Please review the Administrator Guide, ''Customizing Quality Center Projects'' and concentrate on the section about adding User-Defined fields.

Please let me know if this resolves the issue.