Thanks for sharing the credentials. I checked your site and found out that this issue is coming from a third party plugin only.
Please refer this:
http://prntscr.com/cb1b1m, this is my test setup edit page and there is no tinymce.min.js file on this page, as we do not use this file here.
But on your page it is present with the compact3x which indicates that some plugin is using this file, an older version of tinymce because compact3x is used to make tinymce old version compatible with the new version of wordpress, refer:
http://prntscr.com/cb1ciw
So this issue is related to the third party plugin as wplms do not use this file here.