Can't copy files to WD My Passport 2TB (Mac)

This is a new external drive which I have just purchased. I formatted it for Mac and it seems to be working with Time Mchine no problem. However, when I try to drag and drop folders and files to the external drive, I’m asked to ‘authenticate’, then I get the following message:

The operation can’t be completed because one or more required items can’t be found.
(Error code -43)

I’m sure I formatted it as per the WD instructions ‘Mac OS Extended’.

If anyone can help, I’d much appreciate it. Thank you!

Hello,

I recommend you reformat the drive then try again.