Live Photos created with PHLivePhoto API show "Motion not available" when setting as wallpaper

I'm creating Live Photos programmatically in my app using the Photos and AVFoundation frameworks. While the Live Photos work perfectly in the Photos app (long press shows motion), users cannot set them as motion wallpapers. The system shows "Motion not available" message.

Here's my approach for creating Live Photos:

// 1. Create video with required metadata
let writer = try AVAssetWriter(outputURL: videoURL, fileType: .mov)
let contentIdentifier = AVMutableMetadataItem()
contentIdentifier.identifier = .quickTimeMetadataContentIdentifier
contentIdentifier.value = assetIdentifier as NSString
writer.metadata = [contentIdentifier]

// Video settings: 882x1920, H.264, 30fps, 2 seconds
// Added still-image-time metadata at middle frame

// 2. Create HEIC image with asset identifier
var makerAppleDict: [String: Any] = [:]
makerAppleDict["17"] = assetIdentifier  // Required key for Live Photo
metadata[kCGImagePropertyMakerAppleDictionary as String] = makerAppleDict

// 3. Generate Live Photo
PHLivePhoto.request(
    withResourceFileURLs: [photoURL, videoURL],
    placeholderImage: nil,
    targetSize: .zero,
    contentMode: .aspectFit
) { livePhoto, info in
    // Success - Live Photo created
}

// 4. Save to Photos library
PHAssetCreationRequest.forAsset().addResource(with: .photo, fileURL: photoURL, options: nil)
PHAssetCreationRequest.forAsset().addResource(with: .pairedVideo, fileURL: videoURL, options: nil)

What I've Tried

• Matching exact video specifications from Camera app (882x1920, H.264, 30fps)
• Adding all documented metadata (content identifier, still-image-time)
• Testing various video durations (1.5s, 2s, 3s)
• Different image formats (HEIC, JPEG)
• Comparing with exiftool against working Live Photos

Expected Behavior

Live Photos created programmatically should be eligible for motion wallpapers, just like those from the Camera app.

Actual Behavior

System shows "Motion not available" and only allows setting as static wallpaper.

Any insights or workarounds would be greatly appreciated. This is affecting our users who want to use their created content as wallpapers.

Questions

1. Are there additional undocumented requirements for Live Photos to be wallpaper-eligible?
2. Is this a deliberate restriction for third-party apps, or a bug?
3. Has anyone successfully created Live Photos that work as motion wallpapers?

Environment

• iOS 17.0 - 18.1
• Xcode 16.0
• Tested on iPhone 16 Pro