title: Page editing redirects to Posts page (edit.php)
body: <p>Just today, when I went on to edit one of the pages on my Wordpress <a href="http://eadcdigitalbridge.org" rel="nofollow noreferrer">website</a>, and it redirected me to the Posts page (edit.php) when I pressed Update or Preview Changes and did not save my changes. I have ruled out the problem being related to any of my plugins because it persisted when I deactivated all of them, and I have ruled out the Theme the same way. Even reinstalling the WordPress version did not fix this. The last edits made to the site were on May 20th, and I do not know whether something in WordPress changed between then and now. Another thing to note, I had the site in Debug mode for a while, but I took it out of that and the problem still persisted (using the wp-config.php file). Also, if it helps narrow down, I also cannot update the plugin SiteOrigin Page Builder, it gives the error “Update Failed: 0”, and when I try to edit any widget, all that it shows it "0" on the edit screen; I am not sure if this is connected.  I have seen some answers to similar problems that talked about some problem with the SQL quota on the WooCommerce plugin, but I am not using that at all, so it probably does not apply, unless SQL is used in other ways on Wordpress; I am not enough of an expert to know.  I was also told to make sure my WordPress Address (URL) and Site Address (URL) were configured properly, but I am sure they are because they both match the URL of the site itself, and I could not change it if I wanted to, Wordpress is ignoring those changes as well.  It also ignores changes to Users made from the Admin Dashboard; I have not checked to see if changes to Users from the front-end is possible.</p>
  
  <p>Any insight will help, this problem is quite maddening because I have some pages that need changes, and I cannot find a way to accomplish that.</p>
  
  <p>Sorry for the long question and thank you in advance!</p>
  
  <p>Plugins installed:
  Akismet Anti-Spam,
  Category Posts Widget,
  Cleverness To-Do List,
  Duplicate Page,
  Easy Google Fonts,
  Google Analytics for WordPress by MonsterInsights,
  Hello Dolly,
  Jetpack by WordPress.com,
  MOJO Marketplace,
  Ninja Forms,
  OptinMonster API,
  Page Builder by SiteOrigin,
  SiteOrigin Widgets Bundle,
  Smart Slider 3,
  Ultimate Member,
  Wordpress File Upload,
  WP User Frontend,</p>
  
  <p>Theme used:
  Sparkling</p>
  
  <p>Edit: I recently noticed that when trying to push the Update on the page, it returns a "400: Bad request" error on "POST" from admin-ajax.php, may be related.</p>