Hello there,
Can you please try the Chrome browser and again make sure that it is 100% cleared of any cache.
Do you have phpMyAdmin? CJT will never just delete your code blocks as they are stored in the database.
It will only delete your code blocks if you checked the ‘Wipe out Data’ in Settings (cog icon), then Deactivated and Deleted the Plugin. But if you did not do that, then your codes should be safe.
Also try these general troubleshooting ideas below:
– make sure you are running PHP version 7.1 or higher
– increase your PHP Memory limit to 128MB or even 256MB: https://www.wpbeginner.com/wp-tutorials/fix-wordpress-memory-exhausted-error-increase-php-memory
– make sure you don’t have any security plugins getting in the way – e.g. preventing AJAX from working in the Admin dashboard.
– deactivating plugins one by one
– deactivate your theme
Lastly and this is a long shot, according to this support post here, it could be one of two things:
1) The file ‘jquery.block.js’ could be missing in the plugin during the plugin update. Added/modified necessary files in the plugin folder. You may need to download the plugin manually and add that file in.
2) There may be a JS file that seems to be looking for a CSS selector which is apparently missing. The selector class is ‘postbox-header’. Removing that CSS class reference from the JS file may fix the issue. This could be something to do with an older version of WordPress or some other plugin that might be removing that class from the admin area.
If you can post any errors from the CJT dashboard page via the console, that may help.
Thanks