Thanks for your help,
I am trying to make it work with qtranslate (I have qtranslate-X and acf qtranslate). So I disabled qtranslate and the ACF WYSIWYG field works well even if the error still appears in js console. But when I reactivate qtranslate, all the WYSIWYG fields are missing the toolbar.
Do you still have this problem ?
I have exactly the same error and can’t find the solution.. if anyone has an idea to fix this please let me know.