Hi Tahzeeb,

I have tried this on my PDI and it works. Can you try-

1. Create a 'Before' 'Insert' BR on 'incident_task' table and add the script:

current.work_notes = current.incident.work_notes.getJournalEntry(-1);

2. Create an 'After' 'Update' BR on 'incident' table with filter condition 'Work Notes changes' and add the script:

var incTask = new GlideRecord('incident_task');
incTask.addQuery('incident', current.sys_id);
incTask.query();
while(incTask.next()){
incTask.work_notes = current.work_notes.getJournalEntry(1);
incTask.update();
}

Test Scenarios:

When I created incident I added the work notes "Test 1, Test 2, Test 3" and then I created an incidnet task:

Incident Task:

Then I updated the work notes on Incident as "Test 4" and "Test 5"

Incident Task:

Incident for your reference: