Three computers running current version of Firefox. All have a longstanding bookmark for Google Calendar. Starting this morning, when I click on the bookmark, Calendar goes into a "loading" mode and will not load. However, when I open Gmail using the same sign-in I can access the calendar in the right pane of the Gmail page. But when I try to open the calendar in a new tab, the same "loading" issue happens and I can't see a full page calendar. Two computers run on Windows 10, one on Windows 7. All three computers have the same problem which has never happened before. I have tried adjusting Firefox privacy settings on each computer to no avail. I run a Malwarebytes VPN and have tried turning that off, but have the same result. I don't think this is a Google problem because the right pane calendar opens fine when I open Gmail. I also tried this in Microsoft Edge on the two Windows 10 computers and the calendar opens fine. The calendar data also opens fine in third party ios calendar apps. So I'm at a loss about what to try next.