Foundation model sandbox restriction error

I'm seeing this error a lot in my console log of my iPhone 15 Pro (Apple Intelligence enabled):

com.apple.modelcatalog.catalog sync: connection error during call: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.modelcatalog.catalog was invalidated: failed at lookup with error 159 - Sandbox restriction." UserInfo={NSDebugDescription=The connection to service named com.apple.modelcatalog.catalog was invalidated: failed at lookup with error 159 - Sandbox restriction.} reached max num connection attempts: 1

Are there entitlements / permissions I need to enable in Xcode that I forgot to do?

Code example

Here's how I'm initializing the language model session:

private func setupLanguageModelSession() {
  if #available(iOS 26.0, *) {
    let instructions = """
      my instructions
      """

    do {
      languageModelSession = try LanguageModelSession(instructions: instructions)
      print("Foundation Models language model session initialized")
    } catch {
      print("Error creating language model session: \(error)")
      languageModelSession = nil
    }
  } else {
    print("Device does not support Foundation Models (requires iOS 26.0+)")
    languageModelSession = nil
  }
}