Localization: "Add All" gives no feedback when the project contains no Locale assets - the click appears to do nothing

Steps to reproduce:

1. Create a new project
2. Install the Localization package (com.unity.localization)
3. Open Edit > Project Settings > Localization and click "Create" to make the settings asset.
4. Verify that "Available Locales" reads "List is Empty"
5. Click "Add All"
6. Watch the "Available Locales" list, the Console, and check for any dialog or message

Actual results: Nothing happens, and nothing is reported. The list refreshes unchanged and still reads "List is Empty". No dialog appears, no Console message is logged, and nothing explains that the button registers Locale assets already present in the project rather than adding cultures. Sitting between "Add Locale" and "Add Custom Locale", which both open a window, the dead click reads as a broken button

Expected results: The button is disabled while no unregistered Locale assets exist, or it reports the outcome - for example, "0 Locale assets found in the project"

Reproducible with versions: 1.5.12 (6000.5.7f1, 6000.6.0f1, 6000.7.0a6)

Tested on (OS): MacBook Pro - Tahoe 26.6.2

Notes: The button's tooltip does read "Add all Locale assets in the project", but a tooltip does not explain a click that appears to do nothing - the user has to hover deliberately to find it, after the click has already failed.