Repeating tasks don't work properly

I've crated several repeating tasks with next repetition settings: frequency - daily. 

After week I understood that I do not have these tasks on weekends so I changed frequency to weekly with next days: Mon, Tue, Wen, Thu, Fri. After clicking OK tasks setted randomly to different days. And now I can't set these tasks to days I need. Each time I try it sets randomly.