BAT Calendar Reference: How to set order of rooms in Month View?

I have a calendar node with three "BAT Calender Unit Reference" fields ordered like this:

I would expect that this would result in the bars showing availability would be stacked like this:

1. Room 1
2. Room 2
3. Room 3

However the ordering the bars in the calendar node seems to have no effect and on my site, they show up ordered like this:

1. Room 2
2. Room 3
3. Room 1

The problem is illustrated in the two screenshots below. The top screenshots shows the room when I as an administrator visit the "Manage Rooms Availability" page. It shows the rooms stacked in the correct order from top to bottom.

However, the view presented to the end user, when I am displaying availability to end users by having all three rooms included as fields in a single calendar node, the order appear as random (Room 2 is on top, Room 1 is at the bottom, with Room 3 in the middle).

How do I control the stacking order of the rooms when they appear in Month View of the calendar?