System Information
Operating system: Ubuntu 21.10
Graphics card: Mesa Intel Xe Graphics (TGL GT2)

Blender Version
Broken: 3.1.0
Worked: 3.0.1

Short description of error
When you duplicate a grouped strip that have some element with F-Curve keyframes, they are lost.

Exact steps for others to reproduce the error
In the video you can see the steps:

Create a strip and add some animation to it. For example, add Translate and set some X values.
Duplicate them. You can see that the animation is correctly duplicated.

Now group the initial strips and duplicate it. You can see that the duplicated strip loses the animation.