If you have a touchscreen computer on Windows using Chrome, you may be unable to drag-and-drop categories with the touchscreen, but can only drag-and-drop categories with the mouse. To fix this issue, you need to disable touch events in Chrome.

Type chrome://flags in the Chrome address bar and press ENTER

Locate Enable touch events > Change the option to Disabled

If you host your website in a WP Engine server the file preview may not work.
This is because WP Engine tries to redirect bots crawling and Google Drive Viewer may be detected as a bot crawling.

In this case please contact WP Engine Support team and ask them to disable redirect bot feature.

If you host your website in a WP Engine server you may encounter 404 errors on some type of files.
This is because WP Engine uses a proxy with a particular configuration.

First of all, if you have changed the default SEO url in the plugin configuration page, please note this value and replace it in the first line of the code we provide in the next lines: (location ~* ^/replace_here_if_you_have_changed_it/* {).

Then please contact directly the WP Engine support https://wpengine.com/support/ and provide this information:

We use the WP File Download plugin from Joomunited. When this plugin is used under your environment we encounter 404 errors when we try to download files managed by this plugin.

This question has already been asked to the WP Engine and you fixed it for other customers according to the following explanation.

The WP File Download plugin generates files url that are processed by a php script.
For example: /downloads/14/category/11/file.pdf is internally redirected, by the default htaccess rules, to the main index.php file.

But as you're serving static files through an Nginx proxy and if the file is not found, the proxy returns a 404 error and the index.php script is never called.

In order to fix this 404 error, we need you to add to our site's "Before" rules these lines. 

location ~* ^/download/* { proxy_pass $dynamic_upstream_read_only; }

Yes it is, it's a feature you can activate in the global parameters: "activate remote download". Then you can add a remote file like any other local file (both can be mixed), define a title, an URL for the file, an extension type (for the icon, zip, xls...).