This bug was introduced when the feature was written. The wireframes only showed a button with the first file, so the button was coded that way. However, the button then showed with every file. The original implementor couldn't figure out how to remove it for all the other files. At some point people decided it was fine to leave it with all the files, having lost the context that the button didn't work for the rest of them.
The button only works for the first file.
This bug was introduced when the feature was written. The wireframes only showed a button with the first file, so the button was coded that way. However, the button then showed with every file. The original implementor couldn't figure out how to remove it for all the other files. At some point people decided it was fine to leave it with all the files, having lost the context that the button didn't work for the rest of them.
upstream at https://github.com/projecthydra/sufia/issues/3031