Thanks, the material in use is M_Ocean_Ultra"
I’m actually trying it again with the default Project on the “IslandMap” and UE4.18.3
There’s no visible wake behind “BP_Fishboat”, although Shadow Complexity view (F5) shows that the actors for the wake get spawned. I think it’s like that since UE4.16
BTW, if you change the base color of the wake material to a plain red, and the opacity to 1 you can see a slight darker shadow in the water, so the material itself is really there, it’s for some reason just almost invisible…