Ninja multi config expects two (or more?) options

Configuring 'qtbase'
-- Building for multiple configurations: RelWithDebInfo.
-- Main configuration is: RelWithDebInfo.
CMake Error at qtbase/cmake/QtBaseConfigureTests.cmake:40 (message):
  Failed to find compiled architecture detection executable at
  C:/Users/qt/RTA/src-6.0.0/qtbase/config.tests/arch/RelWithDebInfo/architecture_test.exe.
Call Stack (most recent call first):
  qtbase/cmake/QtBaseConfigureTests.cmake:119 (qt_run_config_test_architecture)
  qtbase/cmake/QtBaseConfigureTests.cmake:132 (qt_run_qtbase_config_tests)
  qtbase/CMakeLists.txt:66 (include)
-- Configuring incomplete, errors occurred!