(initially put this is feature request sorry for the duplication)
Repeat from completion is not working when you specify day to repeat on because you are using the due date instead of start date.
Example. Task start on Friday due on Sunday. If you do task on Saturday then and specify repeat every Friday it will be due the following Friday (which is wrong, should be Sunday again). If you specify Sunday then it will loop and recreate itself if done prior to Sunday. If you base the repeat on the start date this will be fixed because the first example would work.