Ok, my prior success with deleting and re-publishing was a red herring. After "rebooting", I hadn't navigated to the correct page to exhibit the erro. The actual problem was that I had 2 different web pages that used the same name for their partial class. When I changed the name of the partial class for login_check.aspx so that it was no longer the same as the partial class name for schedule_interview.aspx, the errors went away.

I don't know why this wouldn't show up as an error in Visual Studio but the problem manifested as follows:

  • Build > Build Website completes without error.
  • Build > Publish Website completes without error.
  • When you navigate to one of the problem pages, you get compile error BC30456: with an error message like 'Title' is not a member of aspfilename.aspx'
and ensuring all partial classes had unique names fixed it.