When importing calendar events from a Microsoft 365 room mailbox (resource mailbox), you may find that events do not appear in meeting rooms.
[Possible Cause]
The admin account cannot read or manage events unless Full Access (Read and manage) permission is granted.
[Suggested Steps]
Ensure that the admin account you are using (for example, admin@yourdomain.com) has been granted Read and manage (Full Access) permission for the room mailbox.
1. Assign Full Access permission to the room mailbox in Windows PowerShell (see Microsoft Exchange section for more details):
Add-MailboxPermission -Identity <resource mailbox> -User <admin mailbox> -AccessRights FullAccess -AutoMapping $false
2. Verify the permission was applied:
Get-MailboxPermission -Identity <resource mailbox> | Where-Object {$_.User -like "<admin mailbox>"}