FolderPicker does not show WSL (Linux) folders, while FileOpenPicker does

[yeelam-gordon]

Describe the bug

FolderPicker (Microsoft.Windows.Storage.Pickers.FolderPicker) does not show WSL (Windows Subsystem for Linux) folders/locations, while FileOpenPicker does show them correctly under the same conditions.

Steps to reproduce the bug

Prerequisites: WSL is enabled and at least one Linux distribution is installed. WSL folders (e.g., \\wsl$\Ubuntu) are visible in Windows Explorer.

1. Launch an app using Microsoft.Windows.Storage.Pickers.FolderPicker (e.g., the StoragePickers sample)
2. Click "Pick Single Folder" to open the FolderPicker dialog
3. Observe: WSL locations (e.g., \\wsl$\Ubuntu) are not shown in the navigation pane or anywhere in the dialog

Contrast with FileOpenPicker:

4. In the same app, use FileOpenPicker → click "Pick Single File"
5. Observe: WSL locations are shown and files inside WSL folders can be browsed and picked

Additional interesting behavior (transient visibility):

6. First, use FileOpenPicker to navigate into a WSL folder and pick any file (e.g., \\wsl$\Ubuntu\home\user\somefile.txt)
7. Immediately after, open FolderPicker again
8. Observe: This one time, WSL folders are temporarily visible in the FolderPicker
9. Close the FolderPicker (pick a folder or cancel), then open FolderPicker again
10. Observe: WSL folders have disappeared again, even though the picker's remembered path (from last use) still points to a WSL location

Expected behavior

FolderPicker should show WSL locations consistently, the same way FileOpenPicker does, matching the behavior of Windows Explorer.

Screenshots

N/A

NuGet package version

Microsoft.WindowsAppSDK 1.8.250916003

Windows version

Windows 11

Additional context

• The FileOpenPicker consistently shows WSL folders — this is a FolderPicker-only issue.
• The transient visibility after using FileOpenPicker in a WSL path suggests the dialog may be caching or inheriting some navigation state, but failing to enumerate WSL locations on its own.
• WSL folders appear as network locations (\\wsl$\...) in Windows Explorer, so this may be related to how FolderPicker enumerates network/virtual shell locations differently from FileOpenPicker.