When using a material with a translucent blend mode, you can not use the lighting modes "Volumetric PerVertex NonDirectional", or "Volumetric PerVertex Directional" and the Tessellation settings "PN Triangles", or "Flat Tesselation" together. Both lighting modes and tessellation can be used separately but print an error when both are used together. The error that is printed is:
This issue does not appear to be a regression
Versions tested: Issue occurs in all versions tested
4.16.3 - CL: 3561208
4.17.2 - CL: 3658906
4.18P2 - CL: 3660543
Head over to the existingAnswerHub thread and let us know what's up.