I found there are two ways to set up resources in Google Calendar.
Like your current set up, one is by setting up the room as an object, thus "rooms" will show up and you can add them to meeting requests.
The other is creating a calendar for the resource, and then adding the room as an invitee to the meeting, thus adding the event to the resource calendar and your calendar. This will also block the resource for use by others during that time slot.
The latter example is achieved by creating the Google calendar for the room and naming it appropriately (example: Large Conference Room) and then in the Google calendar settings, select radio button next to "Auto-accept invitations that do not conflict" and save it. This will allow you to invite the name of the room "Large Conference Room" to the meeting. Just type out the name like you would for any other attendee. If the meeting name does not appear as an option, that means it is already booked or someone from the old "rooms" action didn't update their meeting with the new process.
The ramifications of this could be great, though. All users will need to be retrained on how to reserve the rooms. Any existing meetings will need to be switched to the new method. This also applies to recurring meetings that may have been set up a long time ago. Then the old method will need to be disabled, so that there are no longer "rooms" available to select from on meeting requests. I went through it a year ago, took a few weeks to work out the bugs, but definitely fixed a lot of other issues like yours.