Hi there,
If youRight Click > Inspect the page to open the Browser Developers Tools and view the Elements tab: the <body> tag has the class of blog.
And the grid-* classes only get applied by GP if the template being used is an index or archive template.
Which is odd. I would assume that should be using a Singular template and not an Archive template.
Could you check with TutorLMS to ask why it is using that template ?
In the meantime, add this CSS to fix the width just on pages whose content container have the tutor-wrap-parent class
#page .tutor-wrap-parent {
width: 100%;
}