“Comments” field appears on the top of every Maniphest form when you try to create a new form or try to edit an old one. However, there is no apparent way to unhide this field. This field is not listed under the “Lock/ Hide Fields” option either.
“Comments” field should be listed under the “Lock/ Hide Field” option, so that, it can be enabled.
1- Try to edit a Maniphest task, “Edit” form opens.
2- Click “Configure Form” menu on the top right corner.
3- Select “Edit Form Configuration”.
4- Now you should be able to see the “Hidden” comments field.
5- Click “Lock/ Hide Fields” item from the menu on the right. “Comments” is not listed there.