I guess it should be working unless the new flow has been started on another thread and missing expected page. At this point if you are still on the child case you should have the parent id available so reopening parent might be a possible action.
In the flow can you define the pyWorkCover in pages and classes. I faced this issue in 8.3.1 and it got resolved by this way.
Also, please run a tracer to see the page context when the new flow is being invoked