We found the cause: for Dropbox Business (Team) remotes, RcloneView was addressing the source against your personal namespace rather than the team space during copy/sync, which is why it couldn’t find the folder even though Compare (which uses a different code path) worked fine.
We’ve fixed this. Could you try the build below for your platform and let us know if the copy/sync now completes?
The sync is running, but is very slow. What are the optimal settings for this type of copy? Should I increase the number of file transfers given that it’s copying from Dropbox to Google Drive?