I'm also having troubles with the groups. It seems that the order of grouped events get messed up.
Create a new game, and create a sprite with two animations. one red square and one green square. name them "red" and "green".
Now create these events:
Allways- sprite:set animation to "red"
Allways- sprite:set animation to "green"
and run the app. The sprite will be green.
Now put those events into a group without changing the order. The sprite will be red.
Edit: HAHAHAH! ) so the bug is still there.