NSMenuItem.separator() appears as blank space in Finder Sync extension context menu

Hi,

I’m developing a macOS Finder Sync extension and noticed that NSMenuItem.separator() does not appear to render as a standard separator line when used inside the menu returned from FIFinderSyncController.

In a normal AppKit NSMenu, the separator renders as expected. However, when the same kind of menu is returned from the Finder Sync extension, the separator appears as a blank/full-height empty row rather than a thin dividing line.

Example:

override func menu(for menuKind: FIMenuKind) -> NSMenu {
    let menu = NSMenu(title: "")

    menu.addItem(NSMenuItem(
        title: "First Action",
        action: #selector(firstAction(_:)),
        keyEquivalent: ""
    ))

    menu.addItem(NSMenuItem.separator())

    menu.addItem(NSMenuItem(
        title: "Second Action",
        action: #selector(secondAction(_:)),
        keyEquivalent: ""
    ))

    return menu
}

Expected result:

The separator should render as a normal macOS menu separator line between the two menu items.

Actual result:

In Finder’s context menu, the separator is displayed as blank vertical space / an empty menu row.

I understand that Finder Sync menus are rendered by Finder and may not support every NSMenuItem feature. However, NSMenuItem.separator() is a very standard way to visually group menu commands, so I wanted to ask:

1. Is this a known limitation of Finder Sync extension menus?
2. Is there a supported way to display a real separator line in Finder Sync context menus?
3. Should this be filed as a Feedback Assistant issue against Finder Sync / AppKit?

I’m trying to avoid fake separators such as disabled menu items with "────" as the title, since that does not feel native and may not behave well with different fonts, accessibility settings, or appearance modes.

Thanks!