Just got an error creating a new topic:
"Warning: count(): Parameter must be an array or an object that implements Countable in Notifications_Event->send_all() (line 462 of /home/www/openvehicles/sites/all/modules/notifications/notifications.event.inc)."
Looks like something goes wrong.
Thanks for the notification (sic) of this. It is a fault in the notification module of this forum, and we are trying to fix it. The forum post is registered correctly - just the reporting for how many users were notified is not working.