Timeframes for Dimensions

Hey team,
I currently followed the instructions that allow me to change the date granularity on my looks (https://help.looker.com/hc/en-us/articles/360001288468-Dynamic-Timeframes-for-Dimension-Groups)

The issue however, is that this new dimension does not behave like a date.

As you can see, even if I change my datepicker to Month, I still have a fixed date instead of the month name. I even tried changing the dynamic_timeframe to a date type, but nothing worked.

Also, on top of that, if I order the dynamic_timeframe descending, it does not behave in the same way as the dates.