front end sometimes disconnects from session after stop/run all #2553
Description
When testing the output simulation notebooks from e.g. #2551, I notice that sometimes if I stop the notebook and then hit Run All, it creates a new session but the display and navbar buttons are not connected to it.
It's a "please wait from heck" situation where "Please wait" appears and if I click away, Run button is cycling yellow but no output is appearing and pressing Stop has no effect.
But only sometimes. I speculated that it might be Run All twice, thus interrupting itself like the other From Heck situations, but was not able to repro that way.