Can’t edit older outlook.com calendar events

I can't edit older calendar events in outlook.com.  I use Firefox and IE and have cleared cache, etc. on both browsers, but problem persist.  Also, disconnected sharing to no avail.  The inability to edit occurs with single and repeat events.  I can delete said events and re-establish with desired changes, but that's troublesome.  The re-established events remain editable.

Any suggestions

Thanks