Cant choose sound entities in the level editor

[Wevah]

I can place everything else so far just fine, but I can't assign sounds to sound entities, either through the file selection window or by manually typing them in (e.g., "general_rain"). If I try manually typing the sound name, the name disappears when I press return (unless it's a sound that doesn't exist).

If I edit the .map file by hand in a text editor and add the sound name, it works fine in-game, but the next time I save the map from the editor the sound is broken again.

Is there anything I can do, or is this a bug in the Mac build of the editor?