I have had many errors, "Failed to connect to server" from the code editor.
That has been going on for days.
I have stopped testing add-ons from the code editor, because of the issue with triggers not working from the "test add-on" feature.
But I never want to publish an add-on from a bound script, so I need to copy the code from the bound script over to a stand alone.
I'm wondering if this issue is related to the problem of the browser not being able to determine what account goes with which app in the active browser tab.
Are you logged into multiple Google accounts?