Oufff I think I found the problem
When installing CB 2.0 a new menu group Community Builder is created with several menus. In these menus was cb-login with index.php?option=com_comprofiler&view=login
We used index.php?option=com_comprofiler&task=login with a menu named connexion elsewhere in the menu structure.
These two menus seem to conflict each other and prevent display of subscription options for expired plans.
So removing index.php?option=com_comprofiler&task=login and renaming index.php?option=com_comprofiler&view=login to connexion menu solved the problem
I hope it won't be overwritten in a future upgrade ? thing is that CB 2 should have checked what menu already existed in the whole menu structure before creating new ones.
Will test further