Terraform Genesys: for_each with YAML queue list failing

Trying to spin up queues from a YAML file using for_each, but the plan errors out saying the source isn’t a map or set. Here’s the snippet: resource "genesyscloud_routing_queue" "queues" { for_each = yamldecode(file("queues.yaml")) name = each.value }. The YAML is just a simple list of names. What am I missing?