Google Cloud: google_cloud_instance can't find google_compute_disk

Terraform: 1.0.3

When trying to create google_cloud_disk and google_cloud_instance depending on the disks, snippet from the configuration:

resource "google_compute_disk" "tst-disk1" {
    name         = "tst-disk1"
    image        = "debian-cloud/debian-10-buster-v20210217"
    zone         = "us-central1-a"
    type         = "pd-balanced"
    physical_block_size_bytes = 4096

resource "google_compute_instance" "tst-instance1" {
    name         = "tst-instance1"
    machine_type = "e2-micro"
    zone         = "us-central1-a"
    boot_disk {
        device_name = "tst-disk1"
        initialize_params {
            size = "10"
            image = ""

However, when I do ‘terraform apply’, the instance isn’t created:

Error: Error resolving image name '': Could not find image or family
│   with google_compute_instance.tst-instance1,
│   on line 91, in resource "google_compute_instance" "tst-instance1":
│   91: resource "google_compute_instance" "tst-instance1"

But when I do gcloud compute disks list --format=yaml, the “absent” disk is listed, its selfLink matches the problem one exactly.

How can I make Terraform detect the disk? Using “depends_on” inside instance definition doesn’t help.

Am I the only one who stumbled upon the issue?