Every other time a specific appointment is opened the most recent changes are
displayed without any errors. And, every other time the same appointment is
opened a "Cannot read one instance of this recurring appointment. Close any
open appointments and try again, or recreate this appointment" error appears,
and the appointment displays the appointment without the most current change.

This alternating error occurs with a recurring appointment when a change is
made to one instance of the recurring appointment, such as adding an
additional attendee for one of the weekly meetings.

Any ideas what is causing this and how to resolve this issue?

Thanks!