I chose X-theme with Cornerstone for the following website (launched back in 2015). It was working fine - and just noticed that I am no longer able to edit any posts and pages using Cornerstone... which seems to be holding my content hostage. The website still displays fine, but can't edit. The site has not been moved/migrated since it's launch.
I've tried deactivating plugins - and nothing has changed. I've used different browsers and cleared their caches, and nothing.
The website in question is http://webcomillsupply.com/
The website, themes, and plug-ins are up-to-date as far as I can tell. Here are the plug in versions (current):
Envira Gallery: 1.7.1 (this is currently deactivated, as I can't seem to update it)
Slider Revolution: 22.214.171.124.1 (I've deactivated this one to no effect. I've since reactivated it)
There are a couple more plug-ins, but none that should create a problem. They are: Akismet, BackUpWordPress, Contact Form 7. All are up to date. That's it.
Please advise as to how to fix this issue. It started out of nowhere.