WFM Schedule Group 409 Conflict on AU-1 BYOC

What is the reason this setting causes a 409 Conflict during genesyscloud_wfm_user apply?

Env: AU-1 BYOC
Provider: 2.5.1
TF: 1.6.0

Error: A schedule group with the same name already exists. State is clean. No manual WFM config. Using genesyscloud_wfm_schedulegroup resource. Deployment fails at promotion stage.