Permissions problem viewing photos exported from Photos app new Mac

[Easttime]

I got a new Mac recently and updated it to Sierra. Photos app works fine, it automatically downloaded all our high res photos from iCloud photo library to the new Mac. I then encrypted the internal drive with Filevault2. I can view images fine in Photos. But when I export photos to the desktop and try to open the exported photos there, I get "The file couldn't be opened because you don't have permission to view it". I've been reading around the problem and permissions using Get Info in Finder seem fine. I ran First Aid in Disk Utility (Sierra). What obvious step am I missing? Thanks.