Cannot capture the entire page after upgrading engine from Chromy to Puppet

I just upgrade my backstopjs from 4.0.3 to 6.2.1. And update engine from Chromy to Puppet.

Previously I'm able to capture the entire page with Chromy, but now it can only capture the viewport part. So I have to increase the height of the viewport to capture the entire page.

But it's not working if I need to capture the screen after clicking a button then page scrolling down, the previous view became empty in this case.

Anyone has the same issue and know how to capture the entire page properly for Puppet?