react-modern-birthdays: Modern Employee Birthday Calendar/Timeline webpart doesn't display birthdays

Hello,

I am new to SharePoint and I am trying to implement an employee birthday calendar on SharePoint using the web-part here https://github.com/pnp/sp-dev-fx-webparts/tree/main/samples/react-modern-birthdays

Author of sample is João José Mendes 

Following the instructions in the README.md, I have completed the following steps:

1. Create list Birthdays on root of SharePoint Site with the following columns and properties: 
    
   

2. Create index on column "Birthday"

3. Clone repository from GitHub
4. Launch PS > change directory to .\samples\react-modern-birthdays
5. npm install (no errors)
6. gulp build (no errors)
7. Modify serve.json to include my site's workbench path
8. gulp serve (no issues, but does not display list values)
9. gulp bundle --ship
10. gulp package-solution --ship
11. Add and deploy package to App catalog
12. Approve API Scopes in API Management
13. Add web part to site page

Details about my environment: 

• Developer OS: Windows 10
• Target SharePoint Environment: SharePoint Online
• Browsers: Google Chrome, Microsoft Edge
• Node.js version: 16.19.1
• Required Node.js for sample: 16
• SPFx Doctor results: 

√ SharePoint Framework v1.16.1
√ Node v16.19.1
√ yo v4.3.1
√ gulp-cli v2.3.0
√ bundled typescript used

Any idea on the next step to take? I have surfed the internet and haven't found anything that has helped me resolve this issue.