Using `%gui qt` and calling an async function shows cells as busy even after completion

If I add magic function “%gui qt” or “%gui qt5” at the top of a notebook and I call an async function, it will appear that the function never returns and hangs. The strange thing is that the notebook server is not actually hung and I can run other cells just fine. If I do, then the cell where I call the async function also gets ‘unstuck’ and returns.

A minimum working example is shown below.

I think this is a bug and appears to be similar to this one: Successfully executed cells get stuck in busy state until notebook finishes its run · Issue #4334 · jupyter/notebook (

Shall I create an issue on GitHub, or is another avenue better?

Version info: