Depth of Field artifacts / roughness not affected by blur

Hi everyone

I’m running into a depth of field issue on a cinematic render, where a specific part of the mesh/material isn’t affected by the DoF blur, apparently due to it’s high roughness level (that’s what I’m assuming at least). Tried on/offing all the DoF settings, none had any effect, put scalability settings to the max, also turned off PPV, google came up with no solutions, no idea how to fix that. The camera settings are basically just overtaken from an engine preset. Surely a closeup shot like this should be possible to render without these kind of artifacts? I testrendered it, it’s also rendering like this.
I’m on 5.6.

Grateful for any clues.

If that is a translucent material, you can try to set the translucency pass to Before DOF on the material.