A common reoccurring question we get in support is that there are times where it seems Mobify doesn't work, and websites end up going straight to desktop on mobile. After checking your that your Mobify tag is properly installed, the next thing to check would be if there are any routes leading to the specified page!
To do this, open up a web inspector for the appropriate page, and check the console to see if there is an error message complaining about no matched routes. If so, then this means that the router didn't actually match to any template you defined, which is why you see the page falling to desktop.
You can refer to this document to see how our router works: https://cloud.mobify.com/docs/adaptivejs/the-router/