Decline to Sign | System not showing validation when comments section is added and removed.

Pre-requisites :
1) Template should be created
2) User should send the form

Replication steps :
1) Email triggers on sending form
2) Click on Email link of "Review and complete"
3) Navigate to Edit document page
4) Click on Decline ti sign
5) Add comments in comment text area
6) Remove that comments
7) Click on save

Expected Result : When the comments are added and removed and user clicks on save, system should show validation message