Hi,
This issue is reported to me by one of my customers. When I looked into it, I saw the exact error in JavaScript console. To be clear:
Cannot read property 'coerce' of undefined editor-view.js?ver=4.5.2:17
Cannot read property 'unbind' of undefined plugin.min.js?wp-mce-4310-20160418:1
So wp.media and wp.mce.views variables are undefined according to these errors.
I temporarily disabled JetPack and the issue is gone. Let me tell you about my editor settings if they can be of help fixing this issue.
‘media_buttons’: false,
‘wpautop’: false,
‘remove_linebreaks’: false,
‘apply_source_formatting’: true,
‘convert_newlines_to_brs’: true,
‘remove_redundant_brs’: true