Bug or not : Weird static mesh result in ue5.8 after applying translucent material , more details

as said in title , in ue5.8 stable one , when i apply a translucent material to my static mesh with nanite support , it becomes lowpoly like . which is sawn in ue5.5 and higher. i did a trick to solve this it was import in 5.4 then migrate to 5.5 and higher . it worked until i tested in ue5.8 . what happens? nanite off , mesh isn’t changed , but some faces dissapear , you will say that it’s normal flip , just do two sided but i tried it didn’t work. also normally when it’s normal flip , when you move camera it changes but mine didn’t changes. i verified model. info : OS is win 11 x64 , GPU nvidia rtx 5080 , RHI directX12 , engine version 5.8.0-55116800+++UE5+Release-5.8 .

files :

SM_Chassis_Bus.uasset (1.2 MB)

NewMaterial.uasset (11.8 KB) some mat can be missing but NewMaterial is the bugged material. more info : it 's same result on every meshes either static or skeletal