In some cases, the subject and organizer of a private meeting is shown on the Meetio device even though the above settings are disabled.
This is caused by a parameter in Exchange causing the private flag to be removed.
To fix this, the following powershell command needs to be run for each affected room, replacing "room@yourdomain.com" with the room email address:
Set-CalendarProcessing -Identity room@yourdomain.com -RemovePrivateProperty $false
If you wish to run this on all your rooms at the same time, use:
Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'roomMailbox')} | Set-CalendarProcessing -RemovePrivateProperty $false