gcore_k8sv2 region_name return null

[Mileshin]

I created a cluster using gcore_k8sv2:

resource "gcore_k8sv2" "cluster_name" {
  project_id    = data.gcore_project.project.id
  region_id     = var.region_id
  name          = "cluster_name"
  fixed_network = gcore_network.private_network.id
  fixed_subnet  = gcore_subnet.subnet_k8s.id
  keypair       = gcore_keypair.kp.id
  version       = var.k8s_version
  pool {
    name             = "pool1"
    flavor_id        = var.pool.flavor_id
    min_node_count   = var.pool.min_node_count
    max_node_count   = var.pool.max_node_count
    boot_volume_size = var.pool.boot_volume_size
    boot_volume_type = var.pool.boot_volume_type
    servergroup_policy = var.pool.servergroup_policy
    auto_healing_enabled = true
  }
 }

 variable "region_id" {
  description = "ID for region. Also we can use region_name"
  type    = number
  default = 38 # Frankfurt
}

When I try to use gcore_k8sv2.cluster_name.region_name, I get null instead of region_name.

output "region_name" {
  value = format("Region_name=%s",gcore_k8sv2.cluster_name.region_name) 
}

Example:

│ Error: Error in function call
│
│   on main.tf line 92, in output "region_name":
│   92:   value = format("Region_name=%s",gcore_k8sv2.cluster_name.region_name)
│     ├────────────────
│     │ while calling format(format, args...)
│     │ gcore_k8sv2.cluster_name.region_name is null
│
│ Call to function "format" failed: unsupported value for "%s" at 12: null value cannot be formatted.

It seems to me that this parameter should return the name of the region, as the project_id parameter does for example.