Thank you very much for your response, I appreciate it very much.
Unfortunately neither of the two solutions works.
I have checked as you said that the M_Ocean_Ultra material has “Render After DOF” enabled.
As you said, the Truesky does not have the “Translucency Sort Priority”, and if I change it in BP_Ocean actor (OceanPlane, DepthPlaneUnderside, DepthPlaneTopside meshes) to -1, it remains the same behavior.
Thank you very much for everything, but it seems that doesn’t have a simple solution.