I don't know how many files you have in your MC library, but this job... "Smartlist Task - Missing files" must check that every file is physically present on your drives, which could take a loong time.
MC is not responding because it's busy checking whether or not any of your files are missing. If you wait, it will finish... eventually.
Finally, just to clear up any confusion, could you elaborate on what you mean by "successfully linked"? It's possible there might be a more efficient way to get to your goal.