I have four websites with the same plugin configuration and whitelist rules but I’m unable to upload media from within the Revolution Slider plugin. I checked the folder permissions and they are 755. I am able to upload media through the WordPress Media Manager so I’m not sure why the plugin is being blocked.
My guess would be a file size issue/problem. What is the file type/extension and file size? Maybe Rev Slider has some sort of file size limitation setting/restriction or something else along those lines?
The file size is only 5 megs and my other sites work fine. It won’t allow me to open computer files. If I choose upload file, it won’t take me past that WordPress screen to my computer file.
Yeah 5 MG’s is relatively small these days. Maybe there is a problem with the file itself. ie format or something else like that? So to isolate the exact problem you would want to create other test files using whatever file extension and/or format that the problem file is using. That would simply be to confirm or eliminate a problem with the specific file itself or the file extension type.