Selection from Path not working

[myeyeballsfeellikeboiledeggs]

Hi there, I’m very new to Gimp, have only been using it for 2 days. So, I have this one image of a subject and a green screen background, I’m pretty used to separating things from the background with the pen tool in Photoshop then I convert to selection and voilà. But here I have my selection ready and when I click on Selection from Path nothing happens, yes I’m on Design mode, I’ve tried quitting and re-opening gimp, happens every time

Any idea how to fix this?