Legend labels missing on column chart

Hi Lovely Human!

The labels are missing from my column chart legend.

Here is my short code:
[gdoc key=”https://docs.google.com/spreadsheets/d/1xW8ZGLOpewd34RBUMIjR2kNYUYmIdcsXIwPSLzzM1IA/edit#gid=1866360012″ chart=”Column” header_cols=”1″ header_rows=”1″ chart_legend=”top” use_cache=”no”]

Is my spreadsheet not set up correctly? My first row has years; first column has months. I was hoping the first row (years) would appear on the legend. (Right now months (aka first column “A”) is showing on the h-axis, which is correct.)

Thank you, thank you, thank you

https://wordpress.org/plugins/inline-google-spreadsheet-viewer/