Transient Simulation of Crystal Osc

I'm simulating a 24MHz crystal OSC with spectre APS MMSIM/18.10.397 

I have the startup simulation and ic transient noise simulation which is working fine starting up in 5ms and oscillating without damping to zero with ic.
the problem rises when I tried to study the LDO ripples into the transient simulation using a periodic model file of the ripples in a vpwlf instance as the supply of the circuit. even if this supply is not connected to the crystal and is just present as a floating net. the crystal damps. 

is there any way to properly simulate such a circuit?

vccc1v8_ripple is present in the sch but floating:

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transient noise simulation:

errpreset=conservative

noisefmin=1

noisefmax=1GHz

method=traponly

linearic=yes

oscfreq=24M

relref=alllocal