Cannot edit my homepage index.html in HTML edit any more - blank page

[pcrepai5]

Hello - just lately I cannot seem to edit my Index.html in Html Editor in cpanel now - just getting blank page instead of WYSIWYG editor

https://xo5.x10hosting.com:2083/cps...10host.com&basedir=/home/pcrepai5/public_html

I can use the Text editor though still - any idea what the problem is please? thanks.