Hello. I'm asking here since I've had no luck asking on the official wordpress.org forum ( https://wordpress.org/support/topic/media-upload-filenames-with-foreign-letters-creates-blank-thumbnail/ ) and on StackOverflow ( http://stackoverflow.com/questions/40685147/wordpress-media-upload-filenames-with-foreign-letters-creates-blank-thumbnail )
Everytime I try to upload an image to WordPress that has Æ, Ø or Å the thumbnail shows a placeholder default thumbnail instead of the real image. This happens on a complete new WP install ( xampp localhost ) and it doesn't matter if its WordPress version 4.6.1 or 4.7 and doesnt matter if it's running TwentySixteen or TwentySeventeen theme.
I also tried different MySQL database schemas ( utf8-danish, utf16-danish ) and this doesn't help any bit.
So im starting to believe that the problem is on my XAMPP configuration somewhere.
Please need any advice on what to try from here. Different database schema maybe? Different php.ini settings? Or anything else?