I’ve had the same problem as well.
Noticed it around the same time as I realized that some unknown mod I have changed the C3's draft from the default of nine meters to a more realistic twelve.
Did a couple tests with SH3Inspector and got the C3's wake to show at the default draft. I also tried lowering the draft of the C2 by one meter increments to see if it behaved similarly and sure enough, the wake disappeared at three meters below the default.
I think it may have something to do with the way the game handles the wake texture maybe. :hmm: