When I use a series set to the day of the week num option, the day num for Sun is wrong. So, for this week, which is the 27th to 2nd, the 27th is showing as 03, not 27.
If you have this in every week maybe is a bug, maybe you can post your formula to see if is something wrong.
It's not a formula I'm using. It's the Series control set to the short week num setting. So, add a series container and set it.for the week, hopefully you see the same error.
You are right, in my country weeks start on Monday and the serie is right, but when I change it to start in Sunday I have the same error.
Maybe you can post a bug report, here you have the guidelines