Capacity planning tool that works

[Capps]

Has anyone got any recommendations for how to do capacity planning in Jira Next Gen projects.

I have just wasted 3 weeks reviewing and testing Big Picture.

In the end it turns out that Big Picture does not work with next gen projects correctly. 

So I am back to square one and don't want to spend weeks again testing an addon that might not even work.

What I would like to be able to achieve is:

• Visibility across multiple projects completion rate
• Capacity for the team across multiple projects

Anyone know what actually works with Next Gen projects?

TIA