Entity Framework 6 update record SaveChanges does nothing - asp.net

Question

I am using the following code in an ASP.NET MVC project to update a record (using a JSON call from AngularJS code, but that shouldn't make a difference, right?):
public JsonResult UpdatePerson(Person person)
{
Person pers = db.People.Single(p => p.BusinessEntityID == person.BusinessEntityID);
pers.FirstName = person.FirstName;
pers.MiddleName = person.MiddleName;
pers.LastName = person.LastName;
pers.Suffix = person.Suffix;
pers.Title = person.Title;
pers.ModifiedDate = DateTime.Now;
db.Entry(pers).State = EntityState.Modified;
db.SaveChanges();
return Json(new { status = "Person successfully saved." });
}
When I step through the code, everything looks great for the properties for both the "pers" object and the "person" object. But when I get to the "db.SaveChange()" line, the code just does nothing. I get no error, but I also never get beyond it. It's as if the code just ends.
I've also tried this code that I found, but again, the SaveChanges line does nothing.
public JsonResult UpdatePerson(Person person)
{
db.People.Attach(person);
db.Entry(person).State = EntityState.Modified;
db.SaveChanges();
return Json(new { status = "Person successfully saved." });
}
Any idea what's happening here? It seems from all the articles I've found all over the place that this should work, yet it doesn't. Again: no errors. The code just stops. I never get to the "return Json" line at all.