Toggling a field that makes work note mandatory brings back the applied template which was not visible before. Toggling other drop-downs does not have effect instead, so the issue is due to the Impact / Urgency fields enforcing the work-note to get mandatory, causing the template to reappear.
1. Navigate to System Definition > Templates
2. Create a new template on incident table
a. In the template field, set Worknotes as "test worknote"
b. Save the template
3. Navigate to incident.list
4. Open any incident
5. Apply the template and notice that the worknote field is populated with "test worknote"
6. Delete the contents of the worknote field
7. Apply the template once again
8. Notice that the worknote field is not getting populated
9. Toggle Impact / Urgency field and change the value
10. Notice the template has been applied
After carefully considering the severity and frequency of the issue, and risk of attempting a fix, it has been decided to not address this issue in any current or future releases. We do not make this decision lightly, and we apologize for any inconvenience. If you have any questions regarding this problem, contact ServiceNow Customer Support.