Parallel workflow ending in rejection displays empty tab

1. install 8.10
2. create a File document
3. start a Parallel workflow
4. assign it to the Administrator
5. in the task click Reject
6. in the second task, click again Reject (see beforeRejection.png)
7. this displays an empty tab (see emptyWorkflowTab.png)
8. try to change tab does not make the tab disappear although it is not possible to switch back to the workflow tab unless starting a new one

Note: this does not happen when the workflow ends up with an approval. In this case the workflow tab disappears as expected.