Water plugin : why tree is moving on WaterBodyIsland like a metronome?

I use the water plugin and and I did a basic test : put a tree on an island . The issue is that the tree is moving like a metronome. See video https://youtu.be/-iVnySCO5Pk
How to solve this issue ?
Nota : on the WaterBodyOcean the tree moves also like a metronome but it is acceptable .

I have found the solution: increase the “bound scale” value to decrease the “metronome” .
Nota : the “metronome” is linked to the material used for the static mesh . It could not be reproduced with all the materials.

When the bound scale is increased there is a new issue when the lights are build :

MapCheck: Warning: SM_PalmTree_01_2 Actor casts dynamic shadows and has a BoundsScale greater than 1! This will have a large performance hit

About 99.998% sure you are doing something you shouldn’t be doing within the material for the tree.

The remaining .001% is literally because I never bothered using whatever sorry excuse for a “water system” Epic has been peddling since last year.

And the other .001% is because you could also be doing something wrong in a blueprint or something similar that was added to the level at some point and forgotten.

I highly doubt that the water system is injecting itself into non water materials. It would simply make no sense. And cause all performance for everyone even trying the system to tank below 30fps…

I confirm that the water system and the palm tree used are the source of the “metronome” because I can not reproduce the issue when i use a map without water system with this palm tree (market place => tropical foliage) .
Anyway I have solved the issue by setting the “sway amount bounds” in the foliage and trunk textures used for the palm tree to 0 ( instead of 0.001 )
See picture below: