I recently had a issue logged by a client where a room calendar in Microsoft Exchange 365, when invited to a meeting, shows the organizer's name in the subject instead of the actual subject.
This may well be a desirable feature, but in the case it isn't, this is how it can be resolved.

Room calendars are useful for booking meetings which will take place in a room in an office. Normally, the process would be for somebody to have delegate permissions on this calendar, allowing them to enter a calendar entry into this calendar and invite the required attendees. In this case, everything works well - the room shows the event, including subject and content and invited parties can accept to reject the event depending on their availability.

However, sometimes somebody wishes to create an event in their own calendar, and invite the room calendar to that event. In this case, it appears the default option is for the event in the room calendar to have its subject and content replaced by the organisers details. I'm sure this makes sense in some cases, but my client in this case does not find this desirable. Luckily, there is a solution.

Powershell to the rescue!

A single Powershell command can be used to set some options on a calendar to change the way that calendars processing works.
First, connect to Exchange Online:

Connect-ExchangeOnline

Once connected, you can issue the following command to show the current options for a particular calendar's processing:

Get-CalendarProcessing - Identity "{The Calendar Name}" | fl

Which should show something like the below:

AutomateProcessing                   : AutoAccept
AllowConflicts                       : False
AllowDistributionGroup               : True
AllowMultipleResources               : True
BookingType                          : Standard
BookingWindowInDays                  : 180
MaximumDurationInMinutes             : 1440
MinimumDurationInMinutes             : 0
AllowRecurringMeetings               : True
EnforceAdjacencyAsOverlap            : False
EnforceCapacity                      : False
EnforceSchedulingHorizon             : True
ScheduleOnlyDuringWorkHours          : False
ConflictPercentageAllowed            : 0
MaximumConflictInstances             : 0
ForwardRequestsToDelegates           : True
DeleteAttachments                    : True
DeleteComments                       : True
RemovePrivateProperty                : True
DeleteSubject                        : True
AddOrganizerToSubject                : True
DeleteNonCalendarItems               : True
TentativePendingApproval             : True
EnableResponseDetails                : True
OrganizerInfo                        : True
ResourceDelegates                    : {**Names of delegates are here**}
RequestOutOfPolicy                   : {}
AllRequestOutOfPolicy                : False
BookInPolicy                         : {}
AllBookInPolicy                      : False
RequestInPolicy                      : {}
AllRequestInPolicy                   : True
AddAdditionalResponse                : False
AdditionalResponse                   :
RemoveOldMeetingMessages             : True
AddNewRequestsTentatively            : True
ProcessExternalMeetingMessages       : False
RemoveForwardedMeetingNotifications  : False
AutoRSVPConfiguration                : Microsoft.Exchange.Data.Storage.AutoRSVPConfiguration
RemoveCanceledMeetings               : False
EnableAutoRelease                    : False
PostReservationMaxClaimTimeInMinutes : 10
MailboxOwnerId                       : Room Calendar Name
Identity                             : Room Calendar Name
IsValid                              : True
ObjectState                          : Changed

You'll see there are a few options set to "True" which could be toggled - Delete Subject, Delete Comments and Delete Attachments - they should be fairly self explanitory. You can toggle these options by issuing the following command:

Set-CalendarProcessing -Identity "Room Calendar Name" -DeleteComments $false -DeleteSubject $false -DeleteAttachments $false

This simply disables those options, so now the subject, comments and attachments will not be deleted when the calendar processes the event.
There is one further options which may, or may not, be helpful to disable - AddOrganizerToSubject. This option adds the organizer's name to the start of the Subject. This may be useful, but my client also wanted this switched off which can be done with the following command (or, indeed, adding the flag to the previous command).

Set-CalendarProcessing -Identity "Room Calendar Name" -AddOrganizerToSubject $false

And there we are, new events now will appear in the calendar as desired - with full Subject, Comments and Attachments.
Previous entries will not update automatically, the organizer must go into each one and re-send it (no need to change anything, just re-send it and press "Send Anyway") which will update the event in the room calendar as desired.