Month-to-date report with previous month comparison

I’m using old Opensearch (AWS build) 1.3, but my problem looks the same on official Opensearch playground (so, i suppose, newest possible version)

I used TSVB reports, with Time Series type. Lets use data from “opensearch_dashboards_sample_data_ecommerce”, and “order_date” as time field.

Lets prepare first data series, with count aggregation, and add sibling metric with “cummulative sum”. As time span lets use “last 0 month rounded to month”.

Chart looks great, showing cummulative ecommerce transaction count (green colour)

So i duplicated this series, and in options in “offset time series” provided “1M”.

And this chart looks like this:

almost perfect, except previous month (brown colour) is shifetd one day on the left…

When I provide offset time series “31d”, looks perfect, but unfortunately on next month, this offset will be different.

I’m doing something wrong? Or this is bug I should report?

Is there any alternative option to prepare such report comparing previous month with current month?