file organizer problem: cannot use it to move PDF files from ***\Downloaded\ to the selected folder

I did some search on this topic and found similar situations. However non of them are really solved. Here's the problem I have: I was able to copy all the other PDF files to the selected folder except the ones in the folder ***\Downloaded\. I downloaded them directly from the website (drag the url to Mendeley Desktop). I tried deleting these files from \Downloaded\ and restart Mendeley. The files are reloaded but still in the ***\Downloaded\ folder. I cut and paste all the files from ***\Downloaded\ to the selected folder. It seems to have solved my problem. But why is file organizer not doing the job? The reason why I am writing this is because I like this product very much and would like it to be better. Thank you, Wei