I made a plane and then grouped it. After that, I tested and found that it completely fell apart
If you are making a non anchored
group, make sure to Weld
them together or via Motor6D
.
I recommend using this plugin: RidEdit Lite
If you are making an anchored
group, then just... anchor them... HUH
Click Your group then, go to the top of your screen and press anchored. It should work.