Data tables fixed columns and fixed header not working

debugger99

Hi.. I am trying to fix left 2 columns and fix the header of the table but only either of the one works.. On the initial load or after refreshing the page, vertical scroll works fine. But while I scroll the table horizontally, columns are scrolling but the header doesn't scroll it is just locked to the fixed column headers.
could anybody show an example of using both fixed columns and fixed headers.

Thanks!