Hello,
We have upgraded X theme and its plugins to the latest version. The pages look weird now but cannot be opened and edited with Cornerstone. A new page cannot be created with Cornerstone either. The error message is “The preview was unresponsive after loading. This is most often related to a plugin conflict or aggressive page cacheing.” The memory for Wordpress as suggested by X on other topics - 256M, max limit 512M (settings in wp_config.php). System: OS: Ubuntu, php version: 7.0. WordPress 4.9.8 running. We turned off all plugins except for Cornerstone. Did not help.
What do we do now? Please help.