First of all, make sure that you have notifications enabled in your Profile Settings.
Please note that you can receive notifications only from the language version of the site you are on.
Make sure that the expected notification is not subject to our restrictions:
notifications about new ideas on symbols that you follow are only available on the site. Email notifications have been discontinued;
we don't send a notification if an idea, posted by a user you follow, has been updated. You can receive notifications about an update of a particular idea if you follow it: