I’ve tried dragging a Duplicator package and the first time the import completed, but:
The public directory container a bunch of strange files (e.g. Util_Widget.php, Util_WpFile_FilesystemChmodException.php and so on): they might be coming from the client’s site: I can’t check right now
The site’s custom theme was missing
I’ve deleted the site and tried the import again, this time selecting Apache and PHP 5.6: the import has been stuck on “Adding Site” for about half an hour and there is no clear way in the UI to cancel it, neither any progress showing where it’s stuck on.
I guess that killing Local will solve the last problem, but I’m still unable to import a duplicator package.
Can you please provide your local-by-flywheel.log file?
You can get to it by going to Help » Reveal Local’s Log on macOS. To find it on Windows click on the 3 dots in the upper-right corner of the window then go to Reveal Local’s Log.
Based off of those errors I would recommend re-downloading Local to start with.
Also, can you try checking/repairing your disk using Disk Utility? There are quite a few errors in the log that are indicative of potential disk issues.