The Configurator tab shows a broken link and a message refused to connect. I’ve backed out most changes and cleared my browser cache/cookies with no success.
Have you had a look at the logs of the configurator? New entries should be generated every time you access the configurator. On top of that it would be good to know if you are using hassio or another installation-variant of Home Assistant.
Hah! After closer inspection the menu item was something I added from a tutorial and the URL was bad. I just started to play with HA again after a month break. Need to start from beginning again.