When trying to move a root directory from “Computers” (backups made with Backup & Sync) to My Unit, Google Drive marca “The server encountered an error. Try again later.” The same happens if you try to change the owner.
The partial solution is to create a directory with the same name in My Unit, and move the directory content, that the problem seems to occur only with the root directories, first level.
When moving files from Computers to My Drive, the change will be reflected on your PC (or they will be moved to the trash, if you are not synchronizing that directory of your Unit).
It might be more practical to use hard links to back up directories in My Drive… it would also prevent the Backup restart & Sync every time you add or remove directories.