I am having the same issue with ACF 4.4.11 and IE 11. WYSIWYG editor’s toolbar buttons are not showing. The text inside the editor field is white and therefore appears blank.
Looks like TinyMCE jsut doesn’t load. There is no JS errors on the page. I tried everything that CrisCreixell mentioned. I have also tried to deactivate all the plugins and switch to a default theme. No luck. The problem started after updating WordPress Core from 4.7.2 to 4.8 (4.8.1 – same story). Everything works fine in Chrome
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