Will these commands fix our phantom meetings issue?

I opened a ticket with Microsoft Support for an issue we are facing where "phantom" meetings are appearing in at least two of our meeting room calendars. The subject of the meeting says "Private appointment" and the lock icon appears at the bottom, and when you click on any of them they disappear from the calendar, only to re-appear when you navigate away and come back. They appear in Classic Outlook, New Outlook and Outlook for the web.

The support rep is telling me to run these commands on the room mailbox to "reset the room mailbox availability cache":

Set-CalendarProcessing -Identity <roommailboxupn> -RemoveOldMeetingMessages $true
Set-CalendarProcessing -Identity <roommailboxupn> -AutomateProcessing AutoAccept

But if I run Get-CalendarProcessing, it confirms that these are the existing settings already:

Get-CalendarProcessing -Identity <roommailboxupn> | fl RemoveOldMeetingMessages,AutomateProcessing

RemoveOldMeetingMessages : True
AutomateProcessing : AutoAccept

This can't possibly do anything, right? I should ask my CSAM to open a GetHelp on this case, right?

Does anyone know how to actually fix this issue?