Recurring events in Calendar at iCloud.com are not displaying but they are displaying and updating on all my devices (MacOs and iOS) - any ideas?

For around two weeks, my iCould.com calendar has stopped displaying recurring events. These events are both viewable and changeable on my iMac and MacBookAir; also on my iPad and iPhone. It is just iCloud.com where the recurring events do not display.

This is a new problem for me. I have used iCloud and its predecessors continually. The recurring events are clinics e.g. 'outpatients at faith hospital' 8am - 12 every Wednesday until my retirement age. If I have leave booked, then I delete the clinic for that week only. I have not had this issue for a long time.

If I move the clinic by an hour and then put it back again, the change appears in all Calendar apps including iCloud.com, but a little while later, the event will disappear from iCloud.com again.

Thanks. John