ADRV9009 multichip sync lost after frequency hopping

Hi,

  I'm using a custom board with 3 adrv9009, and I need use their synchronization features.

  Last year, I asked a question :ADRV9009 MCS and RF PLL Phase Sync Question 

  I adopted the srimoyi's suggestions, it worked well and I used it for a while.

  Now I add the frequency hopping function, the 3 adrv9009 FHM configure as GPIO mode , enbleMCS and I can triger 3 chips simultaneously.

  I wrote a test program to make the LO frequencies of the three chips cyclically hop between 600MHz and 800MHz at intervals of 1000ms. I use a signal source and power splitter to input a 601MHz signal to the 6 rx channels. Most of the time, when the LO frequency hop to 600MHz, the ILA data I collected is shown below, It is synced.

  But sometimes , when the LO frequency hop to 600MHz , some chip is not synced , the ILA data I collected is shown below:

  Look CH5 and CH6, they are on same chip and not sync with other channels. But next time,Freq hop back to 600MHz, they are synchronized again. The probability of the problem is about 1/15,,but not fixed.

  Could anyone give me suggustions to solve the problem?