Architect flow import failing with 400 on custom data node

Architect & Flows
1

Can anyone explain why the genesyscloud_flow resource fails during apply? The flow validates locally but the provider returns a 400 on the custom data node.

{
 "id": "custom_data_node",
 "type": "CUSTOMDATA",
 "settings": {
 "key": "user_segment",
 "value": "high_value"
 }
}