This issue has resurfaced for me in ACF 3.5.0, and updating to 3.5.1 didn’t fix it. Any ACF WYSIWYG field in the WordPress page editor shows up as raw HTML with no WYSIWYG buttons above the field. While creating a site, everything was loading just fine, and suddenly this issue surfaced. The ACF configuration shows the fields should be WYSIWYG fields. Any assistance would be most appreciated!
Advanced Custom Fields 3.5.1
WordPress 3.4.2
Firefox 16.0.2 and Chrome 24 on OS X 10.8.2