This has been driving me mad for the last few weeks, every time I went to the editor in WordPress I could only use the HTML tab the Visual tab was blank, just a bare white space.
Tried in Firefox and Chrome but still no joy, then I stumbled over a simple fix which I’d wish I’d known about at the start:
If you add
define( ‘CONCATENATE_SCRIPTS’, false );
to wp-config.php near the top it will work
Ta-da, a simple fix to an annoying problem, hope this can help anyone else out who’s having the same issues.