I am having the exact same issue as described above… here is what happened to me. I had started out using the Twenty Nineteen theme. I had downloaded a few plugins for that, and then decided to switch over to Storefront theme. Storefront made my site look so much better almost immediately. I was very happy with the change. Then i checked it out on my Iphone and the menu for my store caused the pages to show up, instead of all the categories of products from Printful. On mobile it shows a list of items that come from inside wordpress editor, not the menu you set up through customizer. This only happens on cell phones.
The menu does work 100% perfect on PCs and tablets. I have looked everywhere for a solution and this thread is the only thing i have found. If anyone has an idea, feel free to visit our website at https://littlebeltmontana.com/