LTspice has a few kinds of "ideal" models.  I used both kinds.

 

If you used any "real" diode (one with a part number), there's chances of a few factors that could affect results.

 

The ideal diode "D" follows the Shockley diode law, so it is actually pretty close to an actual silicon diode's behavior, but it lacks capacitance and bulk (ohmic) resistance.  That might be what affected your results.

 

Andy