Hi Andrew,
Site notifications are usually sent a minimum of 30 minutes after submission in Moodle, but with a MoodleCloud site, it will not send until the cron service runs for your site.
You can find more information on this topic from the following solution articles: Set up MoodleCloud site activity notificationsSet up MoodleCloud site activity notifications and When crons run in MoodleCloud sites.
Site notifications are usually sent a minimum of 30 minutes after submission in Moodle, but with a MoodleCloud site, it will not send until the cron service runs for your site.
You can find more information on this topic from the following solution articles: Set up MoodleCloud site activity notificationsSet up MoodleCloud site activity notifications and When crons run in MoodleCloud sites.
I hope this information helps.
Regards,
Zuriñe