Setting alternate app icon fails with "Ressource temporarily not available"

Switching alternative app icons previously worked in my app and I did not notice when it broke.

However now the completion handler consistently returns this error if feeding with either an existing app icon name or a fictional one.

Is this a regression I should file a bug report for or am I doing something wrong here?

Include all app icon assets is enabled in the target

Below you can see the error, the .icon files placed in the project navigator, my code and the top of the Info.plist

Thank you

Button("Update icon") {      UIApplication.shared.setAlternateIconName("appIcon_Heart") { error in
    if let error {
      print(error)
    }
  }
}

Error Domain=NSPOSIXErrorDomain Code=35 "Resource temporarily unavailable" UserInfo={_LSFile=LSIconAlertManager.m, _LSLine=113, _LSFunction=-[LSIconAlertManager iconChangeAlertTokenForIdentity:error:]}

Xcode seems to create the correct Info.plist entries.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>BGTaskSchedulerPermittedIdentifiers</key>
	<array>
		<string>newReleasesBackgroundTask</string>
	</array>
	<key>BuildMachineOSBuild</key>
	<string>24G90</string>
	<key>CFBundleDevelopmentRegion</key>
	<string>de</string>
	<key>CFBundleDisplayName</key>
	<string>Hörspielzentrale</string>
	<key>CFBundleExecutable</key>
	<string>Hoerspielzentrale</string>
	<key>CFBundleIcons</key>
	<dict>
		<key>CFBundleAlternateIcons</key>
		<dict>
			<key>appIcon_Heart</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_Heart</string>
			</dict>
			<key>appIcon_RedNoCircle</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_RedNoCircle</string>
			</dict>
			<key>appIcon_WhiteNoCircle</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_WhiteNoCircle</string>
			</dict>
		</dict>
		<key>CFBundlePrimaryIcon</key>
		<dict>
			<key>CFBundleIconFiles</key>
			<array>
				<string>AppIcon60x60</string>
			</array>
			<key>CFBundleIconName</key>
			<string>AppIcon</string>
		</dict>
	</dict>
	<key>CFBundleIcons~ipad</key>
	<dict>
		<key>CFBundleAlternateIcons</key>
		<dict>
			<key>appIcon_Heart</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_Heart</string>
			</dict>
			<key>appIcon_RedNoCircle</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_RedNoCircle</string>
			</dict>
			<key>appIcon_WhiteNoCircle</key>
			<dict>
				<key>CFBundleIconName</key>
				<string>appIcon_WhiteNoCircle</string>
			</dict>
		</dict>
		<key>CFBundlePrimaryIcon</key>
		<dict>
			<key>CFBundleIconFiles</key>
			<array>
				<string>AppIcon60x60</string>
				<string>AppIcon76x76</string>
			</array>
			<key>CFBundleIconName</key>
			<string>AppIcon</string>
		</dict>
	</dict>