The pencil icons used to edit modules is not displayed when a user elevates security privileges to the administrator role. The impersonation button disappears as well during impersonation when the admin role has "Elevated Privilege" checked.
Steps to Reproduce
1) Go to the sys_user_role record for 'admin'. Check the 'Elevated privilege' box.
2) Log into the instance as System Administrator. Click the user's name in the top-right, select 'Elevate Roles', and check 'admin'.
3) Hover the mouse over any module. Note that there is no pencil icon for editing the module.
4) Refresh the page. Note that there is now a pencil icon for editing the module.
This issue will be fixed in an upcoming future release. Please review the Fixed In section to determine the patch your instance can be upgraded when possible. As a workaround, refreshing the page displays the icons and the impersonate button again.
Related Problem: PRB1150319