Paper not including in the list of accepted papers to publish the issue

Description of issue or problem I’m having:
I have added some papers for the publications in the upcoming issue, now when I am trying to add one more paper after complete the editorial flows to add the article in the same issue (earlier list), not able to add it, and a message appear thats screenshot is attached here.

Steps I took leading up to the issue:

What I tried to resolve the issue:
I have refresh the pages, delete the cookies.

Application Version - e.g., OJS 3.1.2:
Current version:

Additional information, such as screenshots and error log messages if applicable:
Attached herewith.

Hi @editor.jnp,

Could you share a screenshot the issue list of articles for this particular issue? Its difficult to see what is going on here.

PKP Team