When I use a filter that selects one or more assigned resources no tasks are displayed in the agenda view. (Even selecting the resource named 'Unassignment' won't display any tasks). Our employees always use such a filter in the 'Tasks list' to find their tasks, so when they switch to the Calendar view it will be empty. We have to clear our filter to be able to use the calendar view. Looks like a bug to me.
Perhaps you filtered the tasks by Resource and along with it set another filter, for example, by Status. After the update all filter settings were automatically reset. As a result you managed to see the tasks in Calendar View.
