Export World doesn't work; creates empty world file.

When I try to use the, "Export World" button on my world, the "Save As" window opens for me to select a file location and name the file. When I click enter a filename and click Export, Minecraft does not give any of the usual exporting prompts in the game that it usually does and it only creates a 0KB world file with the given name.

I've attempted this with multiple worlds and the result is the same for all of them.