We have a group calendar that is shared and managed among several users. One of these share users has created an appointment on this shared calendar but saved it as private.

It appears that with the appointment saved as private, the user that created the appointment is unable to edit or even open this appointment, perhaps because they are not the calendar's owner, and the calendar's owner is also unable to edit or even open the appointment perhaps because they are not the owner of the appointment.

Is there a way to transfer the owner of the appointment to the owner of the calendar or to modify the state of the appointment from private to public? Is there another remedy to allow access and modification of an item such as this?

If my speculation as to the reason it is blocked is correct, it seems buggy that one can create an item like this that results in a permissions block.