Bug ARFoundation not working after loading it programmatically by index

Unity: 2020.3.14f1

ARFoundation: 4.1.7 (base project from https://github.com/Unity-Technologies/arfoundation-samples/tree/4.1)

Reproduced: on Android

Problem:
Automatic XR loading for specific XR loaders does not work for ARFoundation.

How to reproduce

This is the Unity project: https://manyworlds.synology.me/manyworlds/development/tmp/arfoundation-samples-progrmmatically.zip

1. Clone https://github.com/Unity-Technologies/arfoundation-samples/tree/4.1
2. Build scene TogglePlaneDetection to test that it works.
3. Disable "Project Settings > XR Plug-in Management > Initialize On Start-Up".
4. Load XR plugin at index 0 programmatically (snippet bellow).
5. Result: black screen, so no plane detection.
*Expected: the camera should switch on and detected planes should appear on the environment.

Code (CSharp):

1. public void StartXR(int loaderIndex, Action<bool> onFinish = null)
2.     {
3.         if (m_SelectedXRLoader != null)
4.         {
5.             StopXR();
6.         }
7.  
8.         m_SelectedXRLoader = XRGeneralSettings.Instance.Manager.activeLoaders[loaderIndex];
9.         StartCoroutine(StartXRCoroutine(onFinish));
10.     }
11.  
12.  
13.  
14.  
15.     IEnumerator StartXRCoroutine(Action<bool> onFinish)
16.     {
17.         Debug.Log("*** Init XR loader: " + m_SelectedXRLoader);
18.  
19.         var initSuccess = m_SelectedXRLoader.Initialize();
20.         if (!initSuccess)
21.         {
22.             Debug.LogError("*** Error initializing selected loader.");
23.             onFinish?.Invoke(false);
24.             yield break;
25.         }
26.  
27.         Debug.Log("*** Start XR loader");
28.         var startSuccess = m_SelectedXRLoader.Start();
29.         if (!startSuccess)
30.         {
31.             Debug.LogError("*** Error starting selected loader.");
32.             m_SelectedXRLoader.Deinitialize();
33.             onFinish?.Invoke(false);
34.             yield break;
35.         }
36.  
37.         onFinish?.Invoke(true);
38.     }

Attempts

1. Without changing anything in the scene, just adding the manual XRLoader code, doesn't work --> black screen.
2. Delaying ARSession and ARSessionOrigin activation after the XR plugin is loaded successfully --> black screnn; there is an infinite loop because ARSession.state = None.
3. Loading the XR plugin in a scene and changing to the plane detection scene 1 second later (just in case) --> black screen and log bellow

No active UnityEngine.XR.ARSubsystems.XRSessionSubsystem is available. Please ensure that a valid loader configuration exists in the XR project settings.
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:GetActiveSubsystemInstance()
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:EnsureSubsystemInstanceSet()
W/Unity : UnityEngine.XR.ARFoundation.ARSession:OnEnable()
W/Unity :
W/Unity : No ARSession available for the current platform. Please ensure you have installed the relevant XR Plugin package for this platform via the Package Manager.
W/Unity :
W/Unity : No active UnityEngine.XR.ARSubsystems.XRCameraSubsystem is available. Please ensure that a valid loader configuration exists in the XR project settings.
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:GetActiveSubsystemInstance()
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:EnsureSubsystemInstanceSet()
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:OnEnable()
W/Unity :
W/Unity : No active UnityEngine.XR.XRInputSubsystem is available. Please ensure that a valid loader configuration exists in the XR project settings.
W/Unity : UnityEngine.XR.ARFoundation.ARInputManager:GetActiveSubsystemInstance()
W/Unity : UnityEngine.XR.ARFoundation.ARInputManager:OnEnable()
W/Unity :
W/Unity : No active UnityEngine.XR.ARSubsystems.XRPlaneSubsystem is available. Please ensure that a valid loader configuration exists in the XR project settings.
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:GetActiveSubsystemInstance()
W/Unity : UnityEngine.XR.ARFoundation.SubsystemLifecycleManager`3:EnsureSubsystemInstanceSet()