Worknotes field does not show up, although its configured on the form.
Duplicate Activity (Filtered) found on the form
There should be only one Activity (Filtered) configured on the form. If there are duplicate Activity (Filtered), Worknotes will be hidden.
Please also review,
System Property glide.ui.incident_activity.fields and make sure "comments and worknotes"
Checked the User Preference: "glide.ui.incident_activity.fields" and "glide.ui.incident_activity.fields"