I had exactly the same issue, but didn’t get any help from support, and the only other answers I got on the forum where just massively condescending.
I don’t know what I did to actually make it work, I suspect it was when I changed the start day to a Tuesday, this actually made the plan start on the Monday the day before.
I did try playing with volumes etc etc but the only thing I could put it down to was playing with the start date.