I have a number of calendars permanently displayed, but now when I open an email in a new window and then switch to calendar view, all except my original calendar are switched off and I have to reselect them. Very annoying; please fix this a.s.a.p.!
Jacob Sommerville commented
This just started happening a couple weeks ago. Any shared calendars I have selected randomly deselect. I think it started when they reverted opening the calendar in a new window.