Upront Theme - Gallery code cannot be read.

Good day,

I am having trouble with Upront Theme as I do have my custom gallery code and I really like to use it. However, When I try to use the drag and drop feature with the code tab my code does not work or it displays code itself instead of the gallery that I want.

What I did is I just use the old editor and paste my code and it works. But, I need to display it like how the other page width that I have on my site.

Here is the gallery link for reference.