You configured the Email message sent for your alert to include the values from several different columns in your alert list. When users receive the Email, some of the information they expect to see is missing.
In Alert Plus v4.x and higher, you might see Emails with missing information if your alert is configured to alert on a list view.
A current limitation of Alert Plus is that columns defined as Site Columns are not displayed in the Email message.
In Alert Plus version 4.x and higher, when you alert on a list view, the columns included as tokens must be included in the list view. If they are not, modify the list view to make sure those columns are included.
Unfortunately, there is no current resolution for the display of Site Columns in Alert Plus Emai messages.