Extending the Open Loop LLC with Ideal Matrix Trf

I built a full bridge LLC circuit and got things running with matrix transformer.
I find it odd that as I add a matrix cell, the Vo goes down from 12V to 7V(with 16 matrix cells).
Does the ideal transformer see the additional leakage?
Also, any suggestions how to make this faster is welcome.
4E2_LLC_OpenLoop_Initial_FullBridge.qsch (122.5 KB)