There is a lot of boilerplate (duplicated) code in Web Services when handling groups, that area needs a bit of refactor.
Also, when retrieving information, some Web Services allow to specify a group (or allow the WS to determine the user one) but there is no way to obtain all groups information.
One of the existing problems is that the group 0 for the WS means determine group and in the web interface 0 is some times used for all groups.
This is happening in workshop, choice and maybe in the database module (All groups not filtering correctly).
In the feedback module we also have an issue: As teacher, open the analysis and responses report: Analysis WS throws a notingroup error.