On the email Notification form, "SMS alternate" cannot be set to blank once it has been filled.
Steps to Reproduce
1- Hop on to Madrid instance
2- Go To any record on sysevent_email_action (ie System Notification->Email->Notification)
3- Click the "Advanced view" link under the Related links
4- In the "What it will contain" section, for the "SMS alternate" field type "Test" and save
5- Again In the "What it will contain" section, for the "SMS alternate" field, remove "Test" text(from step 4) and save
Expected Result: The "Test" text should be removed from the "SMS alternate" field
Actual Result: The "Test" text is present in the "SMS alternate" field
The issue exists only on the Form view. In the List view can able to set "SMS alternate" to blank. For the workaround, in the list view add the column "SMS alternate" using the "Personalized List" and set the "SMS alternate" to blank for any Notification.
Related Problem: PRB1336681