There have been some JavaScript conflicts in WP4.6 and with other plugins. Can you take a look at one of these threads and contribute there. The developer has been working on the problems and there is a beta version that needs to be tested.
https://support.advancedcustomfields.com/forums/topic/uncaught-typeerror-cannot-read-property-body-of-undefined/
https://support.advancedcustomfields.com/forums/topic/tinymce-error/
