Why does this setting cause 404 on Custom Report API via Terraform?

Context:

Provisioning custom reports via genesyscloud_report_custom on AU-1 BYOC. Using provider v1.19.0. The deployment pipeline uses GitHub Actions to push HCL changes to staging. Most report types (IVR, Agent) apply cleanly. However, when defining a report_type of conversation with specific filter blocks, the initial terraform plan succeeds, but apply fails.

The error is not a 400 or 409. It is a 404 Not Found.

Error: GET https://api.us.genesys.cloud/api/v2/analytics/reports/custom/undefined: 404 Not Found

The ID in the URL is literally undefined. This suggests the provider is trying to read a resource ID that was not returned in the previous create step, or the create step itself failed silently before the read. The JSON payload for the report definition matches the Architect UI export exactly. No syntax errors in HCL.

Question:

Why does this setting cause the provider to lose the resource ID? Is the conversation report type async in a way that the current provider version does not handle? Or is there a missing dependency in the HCL block that prevents the ID from being captured during the create action? Looking for workarounds or known issues in the provider changelog.