Answered
We have a few strange PDFs that have an odd number of pages. When we open the pages panel and display 2 or 3 columns of pages, all of the pages show up by scrolling through them...except the final page! You can use the other page control tools to navigate to it, but not the pages panel. When we change the panel to 1 or 4 columns, then all of the pages show up.
If we add a page to it and make the total page numbers even, it doesn't matter how many columns of pages are showing in the pages panel: each page still shows up correctly.
Anybody have ideas why this buggy issue occurs?
(BTW, I tested this on both Windows and Mac - identical buggy behavior)