windchill workspace "save as" option missing

Version: Windchill 12.1

Use Case: "save as" function in drop down "File" menu is missing in windchill workspace.

Description:

I am trying to save large assy and associated drawings as new assy and drawings In wnidschill workspce. I just noticed  "file"  "save as" option is missing in windchill workspace, it is availabe in commonspace. any solution?