PCG trigger mode reset

I am trying to construct I2S clock and frame sync  by using the PGC in trigger-mode, hoping to synchronize to an external periodic event. 

The very first cycle, the signals are generated as advertized -- 2.5 - 3.5 cycles (of internal sys clk) after the event, both FS and clock transition. 

However, thereafter, they just free run while ignoring the trigger.

Is there a way to make it always re-sync to the trigger, any time the event occurs?

I don't see this addressed in the documentation.