Thanks for joining this conversation, @Millers Lane.

In QuickBooks Online (QBO), the ability to pull up a vacancy report is currently unavailable. As a workaround, you can run the Sales by Class Detail report. However, this will only show the classes (building number) that have transactions entered. You may also consider looking for a third-party app.

Here's how to pull it up:

1. In your QBO account, go to the Reports menu at the left pane to get to the Standard reports tab.
2. Type Sales by Class Detail in the search bar and press the Enter key to open. 

Just in case, I'll add this article for future reference: Run reports.

I'll pass along your suggestion to our Product Developers. They're always looking for ideas from users to consider how to improve QBO. In the meantime, I recommend visiting our Blog site. This is where we share recent happenings and future developments, such as updates to newly added features.

Let me know if you have any other issues or concerns by leaving a comment below. I'm more than willing to assist. Happy holidays!