Sometimes I get a ’phantom selection’ where some closed or crashed browser tab fails to clean up its selection. Even restarting all browsers on all my devices doesn’t get rid of them. Rebooting my Mac also does not help. It prevents me from closing those cells.
I had this happen once. I had the same notebook open in two browsers (chrome open in two screens) and I has some kind of crash (could have been resource hogging what was causing something like a ‘unresponsive tab, do you want to close or wait’) that caused me to close all the browsers.
On restarting, observable thought I still had an open session and so the phantom selection.
It went away after a few days, not sure why, I guess it timed out or something.
Maybe an observable user could examine what instances are active on observable and have the ability to force and end session? (But I don’t know if that how the backend works, so don’t know if that would work.)