Your circuit cannot work like this. A thyristor bridge requires a voltage on the AC side to drive the commutation current that will extinguish one thyristor when you turn on another one.
In your circuit the thyristors will not extinguish (at least not very soon...), so after a while all thyristors will conduct. At this point the phase voltages will be zero. If you wait long enough, the DC voltage will invert (due to the resonant circuit), and the thyristors will turn off once the voltage has reached its negative peak.
I suggest that you use the Probe block to have a closer look at what is going on inside the thyristor bridge.