1.Create a new spreadsheet in your Google Drive
2. Create a Chart (Any chart) will do within the spreadsheet
3. Publish the chart
4. Give the following access permission to the spreadsheet: Anyone with link can view.
5. Open spreadsheet in Sheets app and confirm that the Chart is visible.
6. Open chart in Windows or Mac laptop to confirm it's visible.
7.. now open chart url on Chrome Browser or Firefox browser on any Android device. It won't be visible.
Moderators from Charts dev team : please acknowledge this bug.