Issue with Organization Sharing – Calendar Permission Behavior

Hi team,

I have configured organization sharing between two tenants, Tenant A and Tenant B, to allow users to share availability with each other. However, I am facing an issue:

When a Tenant A user tries to add a Tenant B user’s calendar, they get a permission error.
However, for some Tenant B users, Tenant A users can successfully add their calendars without any issues.
The strange part is that even when a Tenant A user cannot add a particular Tenant B user's calendar, they can still see all availability details of that user in the Availability Assistant.

Does anyone know why this behavior is occurring? What is the correct method to ensure calendars shared via Organization Sharing are viewable?

Also, is there any official Microsoft documentation on this?

best regards,

Farheen Master