When trying to translate a string with QCoreApplication::translate() using the plural forms, lupdate doesn't see it.
For example, 
 

QCoreApplication::translate("Context", "[A] removed %n item(s)", "", static_cast<int>(items));

doesn't show up in QtLinguist after running lupdate. However, 

QCoreApplication::translate("Context", "[A] removed [B] item(s)");

works well.
Using tr() works fine.