DHTMLX grid column freeze option - Header Column Overlap

We have created a grid and we are trying to implement column freeze option in it.
we are trying freeze first 3 columns using below code

mygrid.splitAt(3);

so when we do this the grid gets split into two and freeze is working but when we try to do horizontal scroll the header in leftbox(First 3 fixed columns) is overlapping with the headers in right box(remaing columns).
I have Attached screenshot of the issue. Checkbox, Num, Status are the first 3 fixed columns and others are remaining column.

Please suggest options to resolve this issue.

Attached the screenshot of the issue

Unfortunately the problem cannot be reproduced locally.
Could you please, provide with a complete demo or share with a demo link, where the problem cane be reconstructed.