IntelliJ IDEA hang up after installing plugin CodeGymIdeaPlugin.jar and click any of the six buttons.

recently, I've got the same problem... when I first installed IntelliJ and the plugin, everything worked just fine, but since this morning, tasks i've already solved did not compile correctly anymore... So I reinstalled everything, and deleted all folders, that contained the CodeGym tasks, but it led to the same result. I think we have to solve the task on the website, until there is a solution...