When you using layouts and content pages, especially when copying the layout/content between them you need to be mindful of the Wappler components that are used and if they are included in the header/include script at the top of the content page.
Without seeing exactly what is happening that would be what id look at.
Also, if you have an onclick event in a content page that is referencing something in the layout page, it won’t work In preview mode (like if it opens a modal but that modal component is actually in the layout page)
If you have copied code over and it uses something like Date Picker, it won’t work unless the date picker component had been added through the UI or you add it in the header/include script at the top of the page.
Hope that makes some sense