What is the current behavior?

When combining the stackId + multiple series features, only one area is displayed.

What is the expected behavior?

Expect to get stacked area, similar when using a single data serie

Please provide a demo of the problem in a sandbox

Reproducer https://stackblitz.com/edit/react-qarbpqfn?file=src%2FExample.tsx

Which versions of Recharts, and which browser / OS are affected by this issue? Did this work in previous versions of Recharts?

Rechart 3.0 (not tested on previous version)