LTSpice Zener diode bug?
From the LTspice documentation on .op: 


  There is no guarantee that the operating point of a general nonlinear
  circuit can be found with successive linear approximations as is done
  in Newton-Raphson iteration.


This circuit is non-linear and LTspice fails to detect by itself that Newton iteration fails. Disabling Newton iteration by .options NoOpIter forces LTspice to try different methods for operating point calculations. In this case it opts for Gmin stepping instead and finds the correct result:

Gmin stepping succeeded in finding the operating point.

Semiconductor Device Operating Points:
                        --- Diodes ---
Name:      d1
Model: bzx84b6v2l
Id:     -9.69e-04
Vd:     -6.18e+00
Req:     1.36e+01
CAP:     4.80e-09