I also have this issue. Works fine when moving from 2013-12 to 2014-01, but fails when in going from 2014-01 to 2014-02. When I pulled a trace, the only thing that popped out to me was that the ajax calls are different between the two.
Good ajax call:
action=tribe_calendar&eventDate=2014-01&tribe-bar-date=2014-01
Bad ajax call:
action=tribe_calendar&eventDate=2014-02&tribe-bar-date=2014-03
If I refresh the screen manually and/or direct navigate to the link – works fine so seems to be tied to the ajax call (at least for me).