As per our email sent out on 15th September, it is now possible to upload files from your OneDrive to UBW.
To do this, you will need to follow steps outlined here.
If you have a sharepoint library mapped to your OneDrive, you will also be able to access the files within and directly upload to UBW.
You can also save files from UBW to your OneDrive folders once the drive has been mapped.