multiple ADV7511 are not synchronized

Hi,

  My custom FPGA video board has 4 adv7511 outputs. These adv7511s are driven by the same data[23:0]/hsync/vsync/de/clock sigals as shown in the follwoing picture, when thay are connected to different TVs,  sometimes one TV lost 1 frame and then restore to normal in about 10 seconds. I have read back PLL status, it is always locked. 

The Input ID of ADV7511 is 0, with RGB 4:4:4 inputs. They are connected to a 4-input HDMI monitor which make it easy to observe synchronization problem.

So the question is why different TV are not display the same frame using ADV7511 at the condition of same input signals?

Example: 

 

Best Regards,