We are having issues with column cells aligning properly when using grouping on a grid that contains custom cells. I found an example that shows the issue based on a previously supplied example on this form for showing how to use the features together: https://stackblitz.com/edit/react-we8fax-pmvw9o?file=app/main.js. Basically the cells of the grouped rows are smaller than the headers and there is additional space coming at the end of those rows.