Assume below scenario:
- Create test1.xlsx, input some data with % format.
- Create a chart based the data, then show data table from Chart Tools->Layout->Data table->Show Data Table
- Create a new workbook, named test2.xlsx
- Copy chart from test1.xlsx to test2.xlsx
When you close test1.xlsx, in test2.xlsx you will find percentage (%) format in chart data table and axis changes to numeric format.