Issue: The opportunity fields are visible on the Opportunity Details page for individual opportunities and within the Opportunity Settings.
However, these fields are not appearing under the Select Column tab on the Manage Opportunity page.
Root Cause: If the data type is string and the type is of 1000 characters then it will not be shown under the Select Column Tab in Manage Opportunity Page.
PFB screenshot attached for reference:
Solution : Carefully review the data type and character length of the fields.
