certain HMD angles result in dyn. shadows popping on water surfaces

We are having an issue with shadows from a movable directional light (sun) being cast onto a translucent water surface. In some parts the shadows pop in & out (see video below) depending on the angle of your HMD (you can also see it outside of VR but in VR it’s very noticeable).

Video :

Easy to replicate if you create a empty project, add Epic’s waterpack, apply the transparent water material , place a dynamic light & some meshes to cast shadows on the water surface. Moving around will make certain parts shadow flicker.

We have been trying to fix this for quite some time but haven’t found a solution yet, anyone has any suggestions?