The filter for “is during the previous” includes everything that’s “during” the previous, meaning, including current. Like saying “During this past month” would not mean the same as “Last Month.”
Maybe try the filter: “is before the previous.” This filter sees the present as “0” and last month as 1.
If you entered “is before the previous 1 month” it would look for anything older than August (ie. July and back), so entering is before the previous 0 months will look for anything starting last month.
One day maybe we’ll find a way to visually demonstrate what each filter does especially with is during, is before, is after etc… This certainly requires a better visual guide.
(For future reference this is written in September).