Show the vertical tabs view, the horizontal list of named window icons should be visible
Create two named windows, "A" and "B"
Using the down chevron ("v") at the very right of the horizontal list (see image below), rearrange window B to be before window A
In the horizontal list of named windows, window A is still to the left of window B
Hide the sidebar, then show it again
Window A is now (correctly) to the right of window B

I expect the named window icons to accurately reflect the order of the named windows, without having to "refresh" them by hide/showing the sidebar
Version 0.99.132.3-rc (WebKit 621.1.2.111.4)
Sequoia (15)