HMC7044 sync pin

I have a problem in that my SYNC pin does nothing - unresponsive.  I have read the relevant posts (and others)

https://ez.analog.com/clock_and_timing/f/q-a/19853/configuring-the-hmc7044-sync-input

I have a state machine running off of the OSCOUT0 pins ( at 125 MHz ) that fires the SYNC pin ( tried one and 8 VCXO cycle(s) ).  I have the registers

0x0005 bits [7:6] set to '01' (SYNC. A rising edge is carried through PLL2. Useful for multichip synchronization.)

0x005B set to 0x02 ( SYNC through PLL2  Allow a reseed event to be through PLL2 )

as well as the appropriate bits to enable the channels in question.  The channels respond to a register 'Restart Dividers/FSMs' bit 1 of reg 0x0001.  How can I get the Sync pin to respond and restart the dividers?

TIA

John