QtCreator: CMake FREERTOS_DIR not set (NXP1050 FreeRTOS ARMGCC)

Configuring a project with the MIMXRT1050-EVK-FREERTOS kit fails because the FREERTOS_DIR is not set.

CMake Error at /opt/Qt/QtMCUs/2.0.0/src/app_common/freertos/CMakeLists.txt:20 (message):
Please set FREERTOS_DIR cache entry

In the device requirements the FreeRTOS Sources (IMRXT1050) path is correctly found and valid.

When editing the CMake configuration for the kit, FREERTOS_DIR is not present.