Editable Title does not work!

Hello community,

I am using version 13 and trying to update Purchase Order Title as in the previous version but it’s not working!
All steps is correct like this article:
https://docs.erpnext.com/docs/v13/user/manual/en/customize-erpnext/document-title#fixed-or-editable-titles

the title Omar here is clickable but there is no action when clicking on it!!

Any solution or suggestions?
regards

@OmarJaber the title of purchase order is supplier name , and supplier name is a read only field.

Wow, it worked. Thanks for your help.