I got that error when submitting a purchase requisition workflow the security role is custom
Stopped (error): X++ Exception: Work item could not be created. Insufficient rights for user xxxxx. at SysWorkflowWorkItem-createSysWorkflowWorkItem-createWorkItemsSysWorkflow-saveSysWorkflowQueue-resume
Do you get the same error with the other work flows? We don't know what your custom role has. You need access to this table -> Tables/WorkflowWorkItemTable
What level of access do you have on that table?