How to update pivot table and chart after changing values

Hello,

I have a pivot table and associated chart based on some rows of data. The x-axis in the chart is Year. The rows of data have a column with bimonthly dates (1/31, 3/31, 5/31, etc.) and a Year column. So six rows have a 2020 year, six have a 2021 year, etc. The chart labels the 1/31 data as "Dec-Jan." I previously treated the 1/31 rows as the Jan year, but I decided to change them to the previous (Dec) year.

So, for example, I changed:

To:

But when I go to the chart, select PivotTable Analyze, and Change Data Source, I don’t change anything in the Change Data Source box because I’m pointing to the same range, so I just select OK in that box. And nothing changes in the pivot table and chart. So how do I get the pivot table and chart to update to the updated year values?

Thanks.