One of the use case when a change is rescheduled is cancelling/deleting the workflow and approvals via UI actions and re-starting the workflow.
For the new workflow context, we sometimes notice workflow gets stuck at group approval activity and doesn't assign any approvers.
Workflow will not assign new approves as group approval record that gets generated before canceling/deleting the workflow approvals is available.
Group approval records are created on "sysapproval_group" table.
Before re-starting the workflow make sure the group approval record for the change is deleted.