Jupiter Notebook not properly updating status

Jupyter Notebook executes code, completes, writes output. But the status of the code shows "Running", and this status remains indefinitely. Then, it is not possible to re-run the code, as the previous run is still in Running mode. The only way around this I have found is to close the tab with my code, and start from scratch, every time. What is going wrong here?

Start by reproducing the stuck "Running" state in a Jupyter Notebook and compare the execution status with the completed output. Trace the notebook's execution-status handling to identify where completion is lost; done means completed code is shown as finished and can be run again without closing the tab.

Written by the indexing model from the issue text.