Users have access to Call Steward. While they are logged in they can update their information.

That also means that they can delete their own data. Sometimes they do it without even knowing.

One common accident is when a browser's built in Form Filler, replaces what was previously valid data with no data.

In Call Steward, that appears to be phone numbers.

In your Chrome browser visit chrome://settings/addresses
and verify that the switch is set to OFF

On a mobile device, you accomplish the same through the dotted menu in the Upper Right

Settings>Adressesses and More

Instructions for Safari on MAC can be found here,

Instructions for Safari on iPhone can be found here,

Finally, replace the shortcut for Call Steward on your desktop. 

Here is an instructional video.