We were able to observe this issue. Gridlines are shown in MS-Excel Print Preview when workbook is saved in
Xlsb format. When workbook is saved in Xlsx format, these are not shown.
We have logged this issue in our database for investigation. We will look into it and fix this issue. Once, the issue is resolved or we have some other update for you, we will let you know asap.
It is good to know that this issue is now resolved with the latest version and works fine at your end. Let us know if you encounter any other issue, we will be glad to look into it and help you further.