Try deactivating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.
If that does not resolve the issue, try switching to the Twenty Fourteen theme to rule-out a theme-specific issue (theme functions can interfere like plugins).
Tried both suggestions and no difference. What next?
Try downloading WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.
Apparently it is something with Internet Explorer 10+ so I reported the bug.
Ah, excellent, thanks for the report!
For anyone interested, here is the link to the ticket: https://core.trac.wordpress.org/ticket/27960
