I used the copy method. I highlight the files I want to copy, right-click on the file area, select Send to, then Folder (Copy), and Copy Files to Folder. That was successful with 255 files.
I did run into an issue. 255 files transferred fine, but when I try to do 1,000 I get a synchronization failure with a message that there is not enough room on my E drive. My E drive has almost 9 TB of free space, I don't know how there could not be enough room.