When I use the expression editor, the problem from the print screen happens.
The fields list, as well as the methods list on the right all repeat the same value. Double clicking on them, however, will add into the expression the correct underlying value. This happens both for fields, parameters and variables (and possibly any option I select on the leftmost list). This print was taken from a new blank report I just created to show this problem, it happens on any report I try to edit.