configTIMER_TASK_PRIORITY can be set above configMAX_PRIORITIES. This is probably eventualy catched in runtime by assert in xTaskCreate() if enabled.
This could be catched sooner in compile time which would be nice :).
Problem is different definition of configMAX_PRIORITIES (containing data type). Test demo works correctly if type is removed from definition but i have no idea about possible side effects.
Have a nice day.