I'm hoping somebody else has encountered this or can point me in the right direction, as it doesn't seem obvious what's wrong.
When I go to "batch add files," then select a directory, nothing happens. Well, the screen refreshes, and I can see that the URL has passed the chosen directory through the "startdir" variable to "searchnew.php," and it shows up in the GET debug variables, but the display is exactly the same. This happens with or without the browseable interface.
Other types of uploads work fine, by the way, and this is an upgrade installation where batch add files worked perfectly well at some point, but hasn't been used in a while and I'm not entirely certain what's changed.
I created a test directory with precisely one file and utterly open permissions on the file and directory to rule out anything strange in the filesystem.
PHP is version 5.4.27. Both GD and ImageMagick are installed, for what it's worth, and work fine for single uploads.
There are no errors in the php logs (fully enabled) or apache logs, nor any apparent crashes.