UCC12041-Q1: EMI test issue

Tool/software:

hi TI expert

Here is Hella R&D, We used UCC12041-Q1 for isolated DCDC application

Schematic diagram as below:

Our product failed in RE/CE test , the result as below

Can you support to fix this issue,?

pls. share your comments and countermeasures

Two more question:

1,does common choke inductor mandatory?

2,Why Y capacitor recommended 110pF? theoretically 110pF will pass more high frequency to input power line, which will cause CE test fail more easily

Test result as below

CE fail, 41MHz

RE fail, 57MHz, 227MHz