Custom Upfront Theme Failed to Load CSS and Global Regions

Hi,

I've created a custom theme with Upfront Builder and tried to install it on this site. However, the global theme CSS and global regions weren't loaded in this new site. I checked the theme files and found all the css and global region contents are there. I tried to install the theme to other sites and it just worked normally. So I don't know what happens on this site. Please have a check for me. And I've turned on support access for you.
BR