Tiresome, wont export

“Exception while exporting site”. Just reporting the issue, working on the site very day - upgraded RW to 6.3.5 just now. I can publish, and save but cannot export and wish to work on local Ampps site. No stacks need updating, themes etc, all working normally yesterday.

Message continues:
Error: Could not copy /var/folders/_q/z2n0wn0s3t7b9v7rj_9wc8r40000gn/T/com.realmacsoftware.rapidweaver6/stacks-6BEAFF1A-98AE-49C5-B867-7A1731B51414-ehFW5Y/arrow_down_black.png to /Applications/AMPPS/www/anita/indexnew_files/arrow_down_black.png.

File in question is in every single _files folder, permissions correct - just happens to be the first file in every folder and stops at the first _files folder called indexnew, and same problem if I try to export any page.