The developer can see why it is not working on the problem site—the normal shutdown actions are not firing, which are ordinarily used to trigger the notifications—but cannot identify why they are not. Something to do with some other 3rd party code, caching, the server, who knows.
But he has produced a code snippet that you can use on that particular problem server so that the notifications are triggered earlier.
You will only need to use that snippet (which you can add to Toolset > Settings > Custom Code) on the server that is failing to send the notifications.
Thanks for that - I have added the code to the Toolset > Settings > Custom Code.
However it is producing the following fatal error when we try to navigate to any page:
Fatal error: Cannot redeclare prefix_send_toolset_forms_notifications() (previously declared in /var/www/kle1116-204/apps/dev/wp-content/toolset-customizations/send-toolset-forms-notifications.php:14) in /var/www/kle1116-204/apps/dev/wp-content/toolset-customizations/pretrigger-email-notifications.php on line 13
There has been a critical error on your website.
Sorry, it looks like the developer left active a snippet with the same code.
You can't declare the same function twice.
The snippet they added is "send-toolset-forms-notifications".
You can forget adding it a second time, or if you are managing your custom code some other way you can disable and delete that snippet added by the developer.
Quick feedback for you. We are testing this in various scenarios and are receiving notifications.
We have received some from the English version of our site (default) and also from the German version, which is great news.
I'd appreciate it if we can keep this ticket open for a couple more days while we test all the scenarios (post forms, user forms, contact forms) thoroughly, but it looks like the fix has worked.