GPT using external clock with PWM output

I am unable to obtain a PWM output signal when the timer is clocked from an external input.

Using the SSP I configure GPT0 and GPT2 in PWM mode with GTIOCA outputs enabled.

I open and start both timers in code. A signal is output as expected on both GTIOCA output pins.

I now connect GPT2 GTIOCA (P103) output to POEG1 GTETRGB (P104) input so that GPT2 provides an external clock to GPT0.

In code I open the POEG and set for GPT0 p_gpt_reg->GTUPSR_b.USGTRGBR = 1;

I open and start both timers in code. A signal is output as expected on the GPT2 GTIOCA output pin.

Examination of the POEG registers shows POEGGB.ST toggling confirming the external clock signal.

Examination of the GPT32EH0 registers shows GTCNT cycling through it's count range.

However, there is no signal on the GPT0 GTIOCA output pin.

Have I missed something?

Regards

David