Shift swap approval logic failing for cross-tenancy agents?

Can anyone clarify why shift swap approvals are timing out when agents from different org units trade shifts? The standard workflow works, but cross-unit swaps fail with a 500 error after 30s. We are using the default WFM settings in Genesys Cloud. Here is the relevant config snippet:

swap_policy:
 allow_cross_unit: true
 max_advance_days: 7
 require_manager_approval: true

Is this a known limitation?