After following along a pipeline to completion, if you close the completed results window, it still shows up as running in Branches tab (and activities). The toast never goes away either.
Setup the kzantow/failure-project multibranch pipeline.
Open the pipeline and branches tab
Run the "michaelneale" branch from the branches tab
Click into the running job
Wait for it to finish (karaoke mode)
Close the results screen to return to branches - not that the pipeline says it is still running in the listing, but it isn't.
Repeat the above for a non multibranch pipeline (script below) and you can see the same from the activity tab.
The ATH should be enhanced to cover this case (it looks already for the result screen changing state, but needs to close the tab and check the item in the listing has stopped running).
YOu can see it happening here: