ADRV9025/6 CGS not produced

We are using custom hardware but generating our files using the AD TES GUI. We initialise the ADRV9026 following the example files and proceedure here: and give it the devclk (245.76 MHz) and sysref (30.72 MHz cont.), these both look fine on the scope. The ADRV receives the SYNC low signal (this is confirmed by reading the register bit) but does not start generating CGS (we are probing the JESD lines). We are using profile 90, non-link sharing. SysrefOnStartup is 0. What else should we check? Could incorrect SYSREF phase cause this?