Thanks for the info and I'll open a ticket Monday.
But for anyone encountering the same issue and for @Julia Foran here's what I've done.
- I removed my Outlook Profile and completely emptied my \AppData\Local\Microsoft\Outlook folder of files
- I opened Outlook Desktop and re-setup my account.
- I opened a Room calendar and added a meeting for it at :07. and received an Accept reply. The meeting showed up on my own and the Room's calendar almost instantly.
- I then added another item to the same Room at :09 and received an Accept reply. The meeting showed up on my calendar but not the Room's in Outlook Desktop.
- I verified in OWA and both meetings show up in mine and the Room's calendar.
- The meeting didn't show up in the Room's calendar in Outlook desktop until :18, so almost 9 minutes later.
When doing similar steps (by myself and other users) that time in step 6 can go up to 3 hours before the item shows up in the calendar in Outlook desktop.