We are working with v6.5 of the library and JSS eclipse plugin.
When we export using 'JRXlsMetadataExporter()', the cell background is white and the grid lines are not visible.
Adding the property, 'net.sf.jasperreports.export.xls.white.page.background' with a value of 'false' does not affect the output. We applied the property at both the report and element levels with the same results.
In our testing, we found that the property does appear to function correctly using just the plain 'JRXlsExporter()' method, but we must use the 'JRXlsMetadataExporter()' method to strip the report formatting.