Expressiong group sign missing

[#1]

Did anyone come to a situation when in a chart an expression group sign is missing? I have two different charts in my app. And one of them has the ability to cycle between expressions and the other one has not. I've tried to ungroup expressions and group them again, but nothing is changing..

Any ideas?

[fosuzuki]

Can you post the qvw?

[#3]

Sorry, the app is too big. And data model is too complicated for me to reduce it.