when uploading a file that appear in downloads the file disappears and can't be uploaded

Hi Bruce, 

Welcome to Box Community and happy to assist! 

Looks like you have an issue with the file(s) you've uploaded and downloaded at the same time, am I correct? 

Could you elaborate your workflow for more context? 

We'd love to further assist! 

if I am working on a file I will save it to say "downloads."  then I go into Box and want to upload the file to a Box directory.  When I try to upload the file to Box I see the file as saved in downloads, but when I try to click on to upload, the file disappears from Finder/downloads. If I go directly to downloads I can drag it to Box, but it's more straightforward to seek to upload from Box....