This site had originally been created using another builder by another developer. I was brought in to revamp the site.
When I had installed the Customizr Theme and Nimble Builder plugin, I had modified the original pages instead of creating new ones.
Yesterday, I created a new Home page just to see what happened, and it showed up perfectly. The lesson I learned was build things from scratch. Don’t try to just delete someone’s old work and start new. I created all new pages and the site works fine on mobile.
Certain things look ugly as hell on mobile cause of padding (such as the columns in the Services section), so I’ll probably be changing to something else. But I’m glad that it’s up and running on mobile now.