Can’t access calendars of Office365 mailbox in an hybrid set-up

A while ago, we had some issues with calendar sharing in a hybrid environment.
Users with on-premises mailboxes couldn’t access the calendars of newly created O365 mailboxes.

After checking, we saw that the ACLableSyncedObjectEnabled parameter was set to False. After changing the parameter to True, it still didn’t have any effect.

Upon further troubleshooting, we discovered that the RecipientType of the remote mailbox wasn’t set to ACLableMailboxUser. After changing the msExchRecipientDisplayType value to 1073741824, it suddenly worked without causing any downtime.

To prevent this from happening for new mailboxes, we ran the following command in Exchange Management Shell:

Set-OrganizationConfig -ACLableSyncedObjectEnabled $True

To set this on the existing remote mailboxes:

Get-RemoteMailbox -ResultSize unlimited | Set-RemoteMailbox -ACLableSyncedObjectEnabled

To change the msExchRecipientDisplayType parameter:

Get-Aduser "name" | Set-ADObject -Replace {msExchRecipientDisplayType=-1073741818}

More information on the msExchRecipientDisplayType can be found here:
Recipient type values