When using Special:MovePage at some zoom levels and window sizes, the namespace selection drop-down box appears above instead of below. I guess this is intended but if the box extends above the horizontal line below the navigation menu then that part clashes with the navigation menu and cannot be clicked.
Tested at https://en.wikipedia.org/wiki/Special:MovePage/Example in Firefox, IE and Edge with Vector (first image).
In the Timeless skin (second image) that part of the drop-down box is not displayed at all.
The box is displayed and works in MonoBook, Modern and Cologne Blue.