Can you attach a TWBX instead of the raw data, so we can see what you've done in the side by side bar chart in Tableau?
You'd might consider pivoting your data, so you have one column for "***/Gender" and another for "# of Medal"s". See: Quick Start: Pivot Data from Columns to Rows
Pivoting may still return NULL for the areas where you have no value, but you'll be able to wrap the measure "# of Medals" in the ZN() function, so you get a zero instead of null.
That is how I'd approach it - if you post a TWBX, I can apply a solution for you.
Best wishes and happy analyzing!
Thanks a lot for your response Matt.
here is the link to my public tableau dashboard for you to download the twbx file --> Tableau Public
I got a workaround from one of the community members who suggested simply inverting the axis. however, i feel this a problem with data densification. I'm not aware of zn() function and would like to know what it does.