I did some tests and all worked as expected. Didn't it perhaps undo the crop instead of doing nothing? That would make sense, because the crop tool does not really delete the content, it just hides it.
Automatic Border Remove broken possibly?
I'll just say it doesn't work in Raster images.
I'm not sure why but it doesn't work for me. I took a screenshot and cropped it down, then Eraser Flood painted the surrounding area, then used the border removal tool, but nothing happened. I made sure that I got the edges erased and it didn't work. Any idea what's wrong?