Recently SharePoint has started completely ignoring the filtering criteria in the list view for the Tasks list on my site. For testing, I created a list view with the filter "Show only when the column id is equal to 11." When I look at the list with this view, I see all items in the list although clearly only one should have an ID of 11.
Even the built-in views (Upcoming, Late Tasks, etc.) show all items, though other options like column selection are applied.
Other lists on the same site do not seem to be affected by this issue and if I apply the filters using something like CamlDesigner, I get back the correct (filtered) results.