@Marc - Devoteam Thanks for your reply. It is now working for me.
I had opened a case with Atlassian Support team and they helped to resolve the issue. this was their feedback :-
Our Plans Team has identified the root cause of the issue, where they performed a recent rollout that created these issues with cross-domain calls inside the macro.
I am having the same issue. The error type being displayed is 'failed to fetch'. I have the viewing permissions for the plan as 'all Advanced Roadmap users' which is the only option available.
Welcome to the community.
What is the Jira Plan you have, you require the premium plan to make usage of Advanced Roadmap (Plans) in Jira.
This will allow you to use the Confluence macro.
If you comply to this, I suggest to raise an issue at Atlassian Support, as this most likely is an issue with your instance
Thanks @Marc - Devoteam it is an enterprise version of Agile Jira, so I am not clear what plan it is. I am able to create and maintain the plan in Agile Jira - it is using the macro in Confluence that is not working.
I'll speak with our internal Jira team and see if they know what the issue is.
Let them check if the Jira where the data resides is linked with the Confluence instance where you want to use the macro.