When clicking the "Add Another Item" is not adding the another key value pair fields for the first time (Insertion)

Problem/Motivation

When clicking the "Add Another Item" under the key/value pair fields, it is not adding the another key value pair fields for the first time during insertion. But once added the first value and save the content. For the edit scenario, it is working as expected

Steps to reproduce

* Enable Key/Value field module
* Structure > Block type
* Click the Manage fields in existing block type
* Click "Add field" -> Select the Key/Value (plain)
* Create the field, also set the "Allowed number of values" as "Unlimited" and Save the field settings
* Try to create a block content
* Click the "Add Another Item" and observe the issue.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes