I am guessing it is this error which is causing the TimeMCE on page editor to not be working correctly?
Uncaught (in promise) TypeError: Cannot read property ‘apply’ of undefined
at tN.execCallback (tinymce.min.js?ver=4960-20190918:2)
at yw (tinymce.min.js?ver=4960-20190918:2)
at f.content_style.a (tinymce.min.js?ver=4960-20190918:2)
at tinymce.min.js?ver=4960-20190918:2