Calender not sync on hybird exchange

New Contributor
Calender not sync when try to schdule meeting from on premise to cloud or from cloud to on premise on hybird exchange and getting this error ( unable to schedule event - mailbox not found )
While all configuration for hybrid done , OAuth + federation trust enable to enable free/busy + organization relationship enabled also

Can you help for this please !
2 Replies
Is this a new setup or did it break recently
Yes it’s a new setup