Predictive Outbound Campaign 400 Bad Request on Strategy Config via Terraform

Just noticed that applying genesyscloud_predictivecampaign_outbound fails with HTTP 400 when setting strategy_config.

Environment: US-1 Prod. Provider v1.15.4.
Error: POST /api/v2/predictivedials/outboundcampaigns: 400 Bad Request.
Payload validation rejects valid JSON for call_flow_id mapping.

Config snippet:

strategy_config {
 type = "PREDICTIVE"
 ... 
}

Is this a known provider bug or API restriction?