std::multimap

I'm having a peculiar problem that has my team concerned about using std::chrono.

We are working with MSVS-13, so C++11.

I have a collection of object states stored in a multimap, keyed by std:chrono::milliseconds. I want to find the last time (largest duration key value) in the map. The obvious answer is to use rbegin():

class ObjectState{};
typedef std::multimap<std::chrono::milliseconds, ObjectState> MapType
main()
{
    MapType stateMap;

    // add some states

    // read the last time
    std::chrono::milliseconds lastTime = stateMap.rbegin()->first;
}

But in my build, this cores. Looking at the debugger, it appears that rbegin() is pointing to an invalid location after the map, just like end() should.

And I confirmed that incrementing the iterator returned by rbegin() does indeed reach the last item in the map.

Everything I read says it ought not behave that way, and if I key the map by "double" instead of by "std::chrono::milliseconds" then rbegin()->first gives the largest time as I'd expect.

Is there some reason for std::chrono and std::multimap to be incompatible?