I have had this problem before but cannot remember how I resolved it. I create a new web form with master page in VS 2012, and when I click on design to view the new form, the master page detail is missing, so in effect I have a blank form. It's only recently happened, and I cannot think of anything that has changed that might have caused it. Can anyone tell me how to fix this?
I have chosen to add the form with master page as usual, and when I check the source it looks as I'd expect
<%@ Page Title="Engineer Entry" Language="C#" MasterPageFile="~/master.Master" AutoEventWireup="true" CodeBehind="EngineerEntry.aspx.cs" Inherits="eis.EngineerEntry" %>
got it sorted, the content placeholder was named incorrectly so did no correspond with that on the master page