Hi @Roger Roger ,
What's the version of the Exchange server?
How did you set the booking policy of room mailbox? Did you specify the specific users?
According to the test in lab environment, I set the specific users could submit in-policy meeting requests or out-of-policy requests to the resource mailbox. Then I could see these users after running the following command.
Get-CalendarProcessing -Identity "room1@contoso.com" | fl
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