Cannot enable autorepair for VM scale set

Question

I'm not able to enable autorepair for my VM scale set configured via Terraform or manually via Azure Portal. Despite having automatic_instance_repair and health_probe_id the autorepair is still disabled in "Health and repair" tab. I've also tried to add it manually in Azure Portal but it doesn't allow me to assign a load balancer rule, either the one created by Terraform or another one created manually. Load balancer probe is just grayed out in the dropdown.

I've also tried to work around it by configuring a healthcheck extension. Unfortunately, it complains that the VMs cannot have both the probe and extension configured. Healthchecks work fine for the instances, only autorepair can't be enabled. Am I missing something here?

Here is the complete Terraform script:

variable "vm_password" {  
  description = "Linux virtual machine root password"  
  type        = string  
  sensitive   = true  
}  
  
variable "frontend_ip_configuration_name" {  
  description = "Frontend IP configuration name referenced by the load balancer"  
  type = string  
  default = "example-frontend-ip"  
}  

# Azure Provider source and version being used  
terraform {  
  required_providers {  
    azurerm = {  
      source  = "hashicorp/azurerm"  
      version = "=3.0.0"  
    }  
  }  
}  
  
# Configure the Microsoft Azure Provider  
provider "azurerm" {  
  features {}  
}  
  
# Configure a resource group  
#  
# All Azure resources have to be part of a resource group.  
resource "azurerm_resource_group" "example" {  
  name     = "example-resource-group"  
  location = "UAE North"  
}  
  
# Configure a VM scale set  
resource "azurerm_linux_virtual_machine_scale_set" "example" {  
  admin_username                  = "exampleadmin"  
  admin_password                  = var.vm_password  
  disable_password_authentication = false # Use password auth instead of SSH keys  
  instances                       = 2 # Default number of instances  
  location                        = azurerm_resource_group.example.location  
  name                            = "example-linux-virtual-machine-scale-set"  
  resource_group_name             = azurerm_resource_group.example.name  
  sku                             = "Standard_B1ls" # Smallest VM for testing purposes  
  
  network_interface {  
    name    = "example-network-interface"  
    primary = true  
  
    ip_configuration {  
      name                                   = "internal"  
      subnet_id                              = azurerm_subnet.example.id  
      load_balancer_backend_address_pool_ids = [  
        azurerm_lb_backend_address_pool.example.id  
      ]  
    }  
  }  
  
  os_disk {  
    caching              = "None"  
    storage_account_type = "Standard_LRS" # Lowest storage tier  
  }  
  
  # Find available images in region with command 'az vm image list' eg.  
  # az vm image list --publisher "Canonical" --offer "Ubuntu" --sku "20_04-lts" --location "UAE North" --all  
  source_image_reference {  
    offer     = "0001-com-ubuntu-server-focal"  
    publisher = "Canonical"  
    sku       = "20_04-lts"  
    version   = "latest"  
  }  
  
  custom_data = filebase64("start_web_server.sh") # Base64 encoded startup script  
  
  # For some reason this currently does not enable self-healing  
  automatic_instance_repair {  
    enabled = true  
    grace_period = "PT10M"  
  }  
  
  health_probe_id = azurerm_lb_probe.example.id # Healthcheck used to determine if instance is healthy  
}  
  
# Configure a subnet  
resource "azurerm_subnet" "example" {  
  name                 = "example-subnet"  
  resource_group_name  = azurerm_resource_group.example.name  
  virtual_network_name = azurerm_virtual_network.example.name  
  address_prefixes     = ["10.0.0.0/24"] # Occupied part of the address space (10.0.0.0 - 10.0.0.255)  
}  
  
# Configure a virtual network  
resource "azurerm_virtual_network" "example" {  
  address_space       = ["10.0.0.0/16"] # Address spaces available for subnets (10.0.0.0 - 10.0.255.255)  
  location            = azurerm_resource_group.example.location  
  name                = "example-virtual-network"  
  resource_group_name = azurerm_resource_group.example.name  
}  
  
# Configure a load balancer  
resource "azurerm_lb" "example" {  
  location            = azurerm_resource_group.example.location  
  name                = "example-lb"  
  resource_group_name = azurerm_resource_group.example.name  
  
  frontend_ip_configuration {  
    name                 = var.frontend_ip_configuration_name  
    public_ip_address_id = azurerm_public_ip.example.id  
  }  
}  
  
# Configure a public IP  
resource "azurerm_public_ip" "example" {  
  allocation_method   = "Dynamic"  
  location            = azurerm_resource_group.example.location  
  name                = "example-public-ip"  
  resource_group_name = azurerm_resource_group.example.name  
}  
  
# Configure a backend address pool  
#  
# This pool manages IPs that will be accessed by the load balancer.  
resource "azurerm_lb_backend_address_pool" "example" {  
  loadbalancer_id = azurerm_lb.example.id  
  name            = "example-backend-address-pool"  
}  
  
# Configure a load balancer rule  
#  
# This rule tells which ports should be used on load balancer and VMs.  
resource "azurerm_lb_rule" "example" {  
  backend_port                   = 8080 # Port of application on the VM  
  frontend_ip_configuration_name = var.frontend_ip_configuration_name  
  frontend_port                  = 80 # Port on which load balancer will receive requests  
  loadbalancer_id                = azurerm_lb.example.id  
  name                           = "example-lb-rule"  
  protocol                       = "Tcp"  
  backend_address_pool_ids       = [  
    azurerm_lb_backend_address_pool.example.id  
  ]  
  probe_id = azurerm_lb_probe.example.id # Healthcheck used to determine if instance is healthy  
}  
  
# Configure a healthcheck probe  
resource "azurerm_lb_probe" "example" {  
  loadbalancer_id     = azurerm_lb.example.id  
  name                = "example-lb-probe"  
  port                = 8080  
  protocol            = "Http"  
  request_path        = "/"  
}  
  
# Output variables printed to the console after apply  
output "lb_public_ip" {  
  description = "Public IP address of the load balancer"  
  value       = azurerm_public_ip.example.ip_address  
}